Furnace

Basics

The aim of this system is to be a modular and OSR compatible framework for people who is new to RPGs and who 5e is too rule-heavy for.
No innovation, I stole nearly everything ('[ ]' marks) and made a set of rules what I think fits a new group the most. I share it, maybe it will give some inspiration to a fellow DM. :)

Important: Every rule is up to the interpretation of the DM. Work out together what fits your group.

Pure Hit Dice [5e HC Mode]

The characters get Hit Dice only until 5th level.

At each Level, roll your class Hit Die and add that to your HP. CON doesn't applies, but it will be at least 1 + CON.

Proficiency and Skills [5e]

Inspired by 5E, with the difference of 1st and 2nd level PROF modifiers. Use Skills as written, but with no restrictions. They are diverse and simple enough to be used effectively.

Simplyfied Experience [DCC]

Choose your favorite system. For my group i use DCC.

Base classes and Archetypes [FTD]

There are only four classes: Fighter, Cleric, Rogue, Magic-user. BUT: You have archetypes (inspired by FTD). Work out these archetypes with your DM, to give your class some flavour. You will see some examples from my games later.

Tables! Tables everywhere

Steal or create your own. Use tables for character traits, crits, fumbles, magic, loot... Everything! Gygax was right!

Actions

Everyone does one thing a turn by large.

Rest

• Short rest: spend one HD
• Long rest: spend and regain all your HD

Death

• When you are bleeding out unconscious for 1d4 round
• When you are reduced to negative (3+LVL+CON)
• When any of your ability scores goes to 0

Initiative

There are two basic possibility: Group Initiative or NO Initiative! See later.

Room DC [ICRPG]

Every encounter has a rating. Every creature's value is based on that rating (ROOM DC): their AC, their SAVE, ALL DC of the encounter.

HARD and EASY [ICRPG]

To handle character strenghts, weaknesses and the context of the attempt , use HARD (+3) and EASY (-3) to modify the ROOM DC. (e.g.: tracking in fresh snow is EASY)

Abstract distance [ICRPG]

The battlefield is zone-based. CLOSE is in melee range; NEAR is, when you can reach an enemy and attack it in the same turn; RANGED is, when you reach your enemy, but cannot attack it, or you can attack it with ranged weapon; FAR is distant, you can only hear it.

Roll to cast and NO Spell levels!

To cast a spell your character has to make a SPELLCHECK (d20 + Spellcasting modifier + PROF). There are no specific spells or spell levels. You should work out your spells with your DM.

I will show you my formula and DCs for the Spellcasting later to give you ideas.

Flow over crunch!

Use only the tools which help you to keep your game flowing.

Often used abbreviations

Abbreviation	Meaning
LVL	Character level
HD	Hit Die
PROF	Proficiency bonus
STR	Strength modifier
DEX	Dexterity modifier
CON	Constitution modifier
INT	Intelligence modifier
WIS	Wisdom modifier
CHA	Charisma modifier
CHECK	Attempt a task, roll a d20
ROOM DC	Difficulty Class of the encounter
EASY	The task is easy, -3 to DC
HARD	The task is difficult, +3 to DC
ATK	Attack CHECK
AC	Armor Class
DAM	Damage
SAVE	Saving throw
CLOSE	Melee range
NEAR	Can reach and attack in the same turn
RANGED	Can only reach or attack with ranged weapon
FAR	Can't reach

Creating a character

Roll Ability Scores

Roll 3d6 six times in order (like in most OSR systems). Calculate the Ability modifiers (mod) as the following table shows:

Abilities and their modifiers

You can go up to 18 on an ability score in natural circum-stances, only magic can bring you above that. You can't go above 20 by any means.

Strength (STR)

Used for doing brute force tasks, moving things, grapling, attacking MELEE targets etc.

Dexterity (DEX)

Used for dodging attacks, climbing tree, sneaking, ranged attacks etc.

Constitution (CON)

Used for resisting poisons, traveling without rest, set your minimum HP / level.

Intelligence (INT)

Shows your general cognitive ability, and is used for casting arcane spells.

Wisdom (WIS)

Shows how sharp your senses are, how insightful you are and is used for casting divine spells.

Charisma (CHA)

Used for perform, lead, decept or persuade, and shows how friendly are people generally to you.

Choose a Race

Human is the 'default'. Race are mainly to give flavour. Create your own. My formula: +1/-1 Ability score, 1 minor racial feature (no Darkvision, Fly or other BS)

Examples:

Human:

• Can swap two ability scores;
• You are PROF with one chosen Skill.

Dwarf:

• +1 Constitution score, -1 Charisma score;
• History or Investigation CHECKS are EASY, when connected to architecture.

Elf:

• +1 Intelligence score, -1 Constitution score;
• Perception CHECKS are EASY, when searching for hidden objects.

Halfling:

• +1 Dexterity score, -1 Strength score;
• CHA CHECKS are EASY, when performing for humanoids.

Half-orc:

• +1 Strength score, -1 Intelligence score;
• Survival CHECKS are EASY, when hunting or foraging.

Character funnel

Create four 0-level characters. Use the rules by Dungeon Crawl Classics. Here is a good video about it from Dungeoncraft. If some of your characters survived the first adventure, they can advance to 1st level and get a Hit Die.

Roll an Occupation

Roll for an Occupation [DCC]. Get a Skill PROF apropriate to the Occupation (like Ditch Digger - Athletics, Blacksmith - Blacksmiths' tools, Beggar - Performace or Deception etc.)

Choose a Class

There are only four classes: Fighter, Cleric, Rogue, Magic-user. BUT: You have archetypes (inspired by FTD). You have to work out these archetypes with your DM, to give your Class some flavor. You will see some examples later.

Pure Hit Dice

Hit Dice are inspired by the man himself, Hankerin Ferinale (5e Hardcore Mode). At each Level, roll your class Hit Die and add that to your HP. No Constitution modifier applies, BUT it will be at least 1 + CON (but cannot be more the half of the character's Hit Die).

Example 1: Fighter with +2 CON. If he advances and he rolls his HD (1d10) and he rolls 1, 2 or 3, he adds 3 to his max HP.

Example 2: Magic-user with +3 CON. If he advances and he rolls his HD (1d6) and he rolls 1, 2 or 3, he adds 3 to his max HP, even though 1+CON is 4 (because HD/2 is only 3).

Choose an Archetype

Work out these archetypes with your DM, to give your class some flavour. You will see some examples from my games later.

Skills

As written in 5E. They are diverse and simple enough to be used effectively, and they give characters flavor.

Proficiency

Inspired by 5E, giving a sense of progression without breaking the scaling of the game.

Fighter

Hit Points

---

• Hit Dice: 1d10 per Fighter level
• Hit Points at 1st Level: 1d10 (opt: 4+CON mod)
• Hit Points at Higher Levels: 1d10 (at least 1 + CON)

Proficiencies

---

• Armor: Light, heavy armor and shields
• Weapons: Simple and martial weapons

---

• Saving Throws: STR + 1 Chosen
• Skills: Choose 1+INT Skills

Class Features

---

• Cleave: If you score a lethal blow, you can deal the remaining DAM to a second target in CLOSE of the killed one.
• Fighting sytle: Choose one of the following:

• (a) Archery: +1 ATK with ranged weapons
• (b) Defense: +1 AC
• (c) Dueling: +1 DAM, when using one-handed weapons
• (d) 2H weapon master: you can roll 1s one time.
• (e) Protection: once a fight a NEAR ally is HARD to hit
• (f) 2 weapon fighting: add ability mod to off-hand DAM

Equipment

For example you can start with the following equipment:

• (a) a martial one-handed weapon and a shield or (b) a martial two-handed weapon
• (a) martial ranged weapon or (b) any simple weapon
• (a) leather armor or (b) scalemail
• a set of adventuring gear (rations, rope etc.)

Cleric

Hit Points

---

• Hit Dice: 1d8 per Cleric level
• Hit Points at 1st Level: 1d8 (opt: 3+CON mod)
• Hit Points at Higher Levels: 1d8 (at least 1 + CON)

Proficiencies

---

• Armor: Light, heavy armor and shields
• Weapons: Simple weapons

---

• Saving Throws: WIS + 1 Chosen
• Skills: Choose 1+INT Skills

Class Features

---

• Divine Prayers: SPELLCHECK (d20 + WIS + PROF). Use the Disapproval Rules from Dungeon Crawl Classics. Maximum number of prayers known: 1+LVL.
• Lay on Hands [DCC]: You can try to HEAL an ally CLOSE to you. On a successful SPELLCHECK, she can use her HD pool to recover hit points (as shown in the table below).

You can use Lay on Hands to heal specific condition (DM discreation) like a broken bone, disease, paralysis, poison etc.

A character cannot be magically healed more HD a day than her level (a 6th level PC can be healed for 6 HD a day). Optional: let the players recover more HD after CON SAVE.

Equipment

For example you can start with the following equipment:

• (a) a mace and a shield or (b) a two-handed mace
• (a) simple ranged weapon or (b) any simple melee weapon
• (a) leather armor or (b) scalemail
• a set of adventuring gear (rations, rope etc.)

Rouge

Hit Points

---

• Hit Dice: 1d8 per Cleric level
• Hit Points at 1st Level: 1d8 (opt: 3+CON mod)
• Hit Points at Higher Levels: 1d8 (at least 1 + CON)

Proficiencies

---

• Armor: Light armor
• Weapons: Simple and martial weapons

---

• Saving Throws: DEX + 1 Chosen
• Skills: Choose 3+INT Skills

Class Features

---

• Expertise: you can choose 2 bonus Skill to be PROF with.
• Sneak Attack: if target is unaware, it is EASY to hit, and the hit scores automatic CRIT.

Equipment

For example you can start with the following equipment:

• (a) one-handed martial weapon or (b) one martial ranged weapon
• (a) simple ranged weapon or (b) one-handed simple weapon
• dagger
• leather armor
• chosen tools (for climbing, dungeoneering etc.)
• a set of adventuring gear (rations, rope etc.)

Magic-user

Hit Points

---

• Hit Dice: 1d6 per Cleric level
• Hit Points at 1st Level: 1d8 (opt: 2+CON mod)
• Hit Points at Higher Levels: 1d8 (at least 1 + CON)

Proficiencies

---

• Armor: Light armor
• Weapons: Simple and martial weapons

---

• Saving Throws: INT + 1 Chosen
• Skills: Choose 1+INT Skills

Class Features

---

• Arcane Magic: An unknown font of magic fuels your spells. SPELLCHECK: d20 + INT + PROF.
  Spell Depletion [ICRPG]: After casting 4 spell, INT SAVE against the ROOM DC, if successful, reset the timer, if fail, you cannot cast until rest (DM discreation).
  Maximum number of spells known: 1+LVL+INT.
• Cantrip: Choose 2 cantrips. These are simple tricks that the character has mastered. NO SPELLCHECK. Non-damage cantrips other systems can be used as is.

Examples: Torchlight, Telekinesis, Illusion, Whisper, Mending etc.

Equipment

For example you can start with the following equipment:

• any simple melee weapon
• sling
• spellbook
• a set of adventuring gear (rations, rope etc.)

Archetypes

You have archetypes (inspired by FTD). You have to work out these archetypes with your DM. Note: don't break the scaling of the advancement, let the magic items do that. These features are to give your class flavour. For DMs: if you wish, you can give an Archetype Feature at 1st level also.

Here are some examples to start your thinking:

Barbarian (Fighter)

Basic Archetype	PROF in Intimidation, Survival
Archetype Feature	Rage: +PROF dam, -PROF AC
	Melee CRIT range 19-20
	HD changes to D12
	Immune to FEAR effects
	Intimidation CHECKS are EASY

Bloodshaman (Cleric)

Basic Archetype	Prerequisite: Half-orc
	PROF in Intimidation, Medicine
Archetype Feature	PROF with a martial melee weapon
	Medicine CHECKS are EASY
	Chosen one: Once a fight reroll an ATK
	Bloodmagic: Convert 1d6 HP to DAM
	Once a fight chosen ally ATK is EASY

Arcane Trickster (Rogue)

Basic Archetype	PROF in Arcana, Insight
Archetype Feature	Weapon counts as magical
	Read arcane scrolls, HARD SPELLCHECK
	Trickster: Learn one cantrip
	SAVE vs. magical EFFECTS are EASY
	Arcane strike: Can use INT for ATK

Wizard (Magic-user)

Basic Archetype	PROF in Arcana, History
Archetype Feature	Spells cast from scrolls are EASY
	Bookworm: learn two additional spells
	Copying spells are cheaper or EASY
	Enchant: Can store a spell in an item
	Arcana checks are EASY

Spells with no levels!

There are no specific spells or spell levels. You should work out your spells with your DM. I show my approach to the Spellcasting. I suggest you to work out with your group what fits your imagination.

My formula

For me magic should be volatile and unpredictable, so I purposefully made non-linear scaling for magic.

I generally use the random spell generation for Maze Rats, here is a good video about that. That book has a lot of cool tables. I work out the base spell with the player based on the generated spell's name. NOTE: I never fully tell the player, how the spell exactly works.

My general rule of thumb: die-based spell effect. The spell has a base effect and based on the "Success Level" of the roll addition dice can be added to that effect. My table:

DC	Success Level	Spell Dice
1	-	Mishapt
2-11	-	Failure
12-15	1	Base Effect (1d)
16-20	2	Base Effect + 1d
21-26	3	Base Effect + 3d
27-31	4	Base Effect + 6d
32-35	5	Base Effect + 10d
36 +	6	WONDER (DM Discreation)

What is the Spell Die? It can be:

• Effect or Duration: d4 (e.g. Shield: 1d4 AC, Bless: 1d4 ATK for 1d4 turns)
• Ranged damage: d6 (e.g. Firebolt: 1d6 fire DAM)
• Melee damage: d8 (e.g. Chill Touch: 1d8 cold DAM)

The Base Effect of the spell is usually one Spell Die. "Major Effects" (e.g. paralysis) can cost more then 1 die. With the increasing Success Level you can combine these dice.
For example Flame Shield at Success Level 3 (4d):

• 1d4 Armor (base effect)
• for 1d4 turns (+1d) and
• it damages the attacker for 2d8 fire DAM (+2d).

NOTE: don't add your modifier (INT/WIS) to the Spell Die, let it be volatile, from a flickering candlelight to a thermonuclear fireball.

SPELLCHECK

• Roll a d20 and and your spellcasting modifier (INT/WIS) plus your PROF.
• Consult with the Spell Effect table.
• CRIT: triple your PROF (i.e.: add double PROF to your SPELLCHECK), and add 2d to the Spell Dice.
• Luck Dice can change your Success Level only by 1!

Note: you need still reach the ROOM DC regardless the Success Level

Examples for Spells

Here are some examples, what I came up with on the fly:

Traditional Examples

Fireball - Ranged Spell

Success Level	Spell Effect
1	1d6 fire DAM               (1d)
2	1d6 fire DAM               (1d) in CLOSE of the target (1d)
3	3d6 fire DAM               (3d) in CLOSE of the target (1d)
4	5d6 fire DAM               (5d) in NEAR of the target   (2d)
5	7d6 fire DAM               (7d) in NEAR of the target   (2d) they go PRONE            (1d) for 1d4 turns                (1d)
6	12d6 fire DAM to everyone NEAR and the survivors run away FRIGHTENED

Chill Touch - Melee Spell

Success Level	Spell Effect
1	1d8 cold DAM                  (1d)
2	1d8 cold DAM                  (1d) the target can't be healed (1d) for 1 turn
3	2d8 cold DAM                  (2d) the target can't be healed (1d) for 1d4 turn                      (1d)
4	3d8 cold DAM                   (3d) the target can't be healed (1d) for 1d4 turn                       (1d) the target is paralyzed       (2d) for 1 turn
5	6d8 cold DAM                   (6d) the target can't be healed (1d) for 1d4 turn                       (1d) the target is paralyzed       (2d) for 1d4 turn                       (1d)
6	10d8 cold DAM the target can't be healed the target is paralyzed until cured

Animate Dead - Effect Spell

Success Level	Spell Effect
1	Still Failure.
2	Rise a zombie                              (1d) for 1d4 turn                                 (1d)
3	Rise 1d4 zombie                         (2d) for 2d4 turn                                 (2d)
4	Rise all NEAR dead as zombies   (5d) for 2d4 turn                                 (2d)
5	Rise all NEAR dead as Revenants(9d) for 2d4 turn                                 (2d)
6	Rise all dead on the battlefield as Revenants and they serve you until they die.

A randomly generated Spell
                                       from Maze Rats

Ember Swarm

Success Level	Spell Effect
1	Summon a swarm of fiery bees: 1d4 fire DAM for 1 turn (1d).
2	1d4 fire DAM                  (1d) for 1d4 turn                    (1d)
3	2d4 fire DAM                  (2d) for 2d4 turn                    (2d)
4	2d4 fire DAM                  (2d) for 2d4 turn                    (2d) target's ATK is HARD     (1d) for 2d4 turns                  (2d)
5	4d4 fire DAM                 (4d) for 2d4 turn                    (2d) target's                            (1d) and others' in MELEE      (1d) ATK is HARD                   (1d) for 2d4 turns                   (2d)
6	Giant Fire Bees attack, set your enemies on fire! 8d4 fire DAM every round, ATK is HARD.

Don't try to balance spells, magic is not balanced. Just have a formula and use it to give a framework to spell creation. The success of the roll and the circumstances of the battle will guide you how the spell will exactly work.

Magical Mishapt [FTD]

You could see how strong magic can be. Only the brave (and the crazy) have the courage to yield such power. Ofcourse, this power has it disadvantages.

When you roll a natural 1, a Magical Mishapt occurs. I suggest you to create your own tables, but I share mine insired by FTD.

General Mishapt Table

d20	Mishapt
1	A random spell is cast (roll d6 for Success Level)
2-3	Caster falls PRONE, DEX SAVE
4-5	Caster becomes WEAK, STR SAVE
6-7	Caster is FRIGHTENED, WIS SAVE
8-9	Caster can’t attempt the spell until REST, INT SAVE
10-11	Caster can't target the same creature until REST
12-13	Caster becomes STUNNED, CON SAVE
14-15	Caster can't cast any spell until REST, CHA SAVE
16-17	The spell affects a random target
18-19	PC/Archetype-specific mishapt (DM discreation)
20	Backfires on the caster (roll d6 for Success Level)

When you create a spell with a player, you can work out a spell-specific Mishapt table. I show you some of my examples.

Optional: you can create spell mutations this way also.

Fireball Mishapt Table

d6	Mishapt
1	No fire, only smoke... (Nothing)
2	Caster creates a gust, knocking her prone, DEX SAVE
3	A fire bubble expodes in the caster's hand, 1d6 damage and caster is FRIGHTENED, WISE SAVE
4	Light explosion: everyone NEAR become blinded, CON SAVE
5	Fireball to a random target (roll d6 for Success Level)
6	The caster is the center of the explosion (roll d6 for Success Level)

Polymorph Mishapt Table

d6	Mishapt
1	The caster grows slimy scales. (Nothing)
2	Caster's voice turns into roaring, can't cast next turn
3	Caster's hands are polymorphed, can't use any object
4	Polymorph another random creature (roll d6 for Success Level)
5	Caster summons the creature instead of polymorph (roll d6 for Success Level)
6	Caster turns herself to a chicken or another critter.

Equipment

Armor and Weapons

Armor and Weapons are simplified and abstracted. You can use the prices and encumbrance values from other OSR systems or 5e.

Use tags [ICRPG] to give weapons flavor (like dagger - tiny). If you feel necessary, you can change the damage and give the weapon some property, like a dagger deals only 1d4 damage, but can be used while grapling and use DEX for the attack.

Examples for TAGs

Weapon	TAG	E.g. prop (create your own)
Handaxe	Thrown	Can ATK NEAR
Sling	Low-range	Can only ATK NEAR
Greataxe	Heavy	DAM: d12, but can't use in 1H
Composite Bow	Recoil	You can add STR to DAM
		etc.

Use ICRPG or Ogres & Oubliettes for inspiration.

Magic Items

Create your own magic items. My formula is similar to my Spellcasting, the only difference is that it scales linearly (only tamed magic can stored in an item made by men).

I have three tier of magic items, and have a Magic Item Die for every tier.

My formula:

A Magic Item Die can be:

• Effect, Duration or Charge: d4 (e.g: Shielding: 1d4 AC, for 1d4 turn with a charge of 1d4 a day)
• Ranged damage: d6 (e.g. Fire arrow: 1d6 fire DAM)
• Melee damage: d8 (e.g. Frost smash: 1d8 cold DAM)

Example Magic Items

Note: a Magic Item Die can bear a curse for the user also.

Other equipment

For other equipment use your favorite system.

Encumbrance

Use the rules from Five Torches Deep or simplify further: your Load is equal 10+STR. Everything counts as one load, except like coins, torches etc. Set the lighter things in bulk and count them as 1 load (1000 coins, 5 torches)!

Gameplay

Meeting NPCs

Use the rules from OSE. Roll 2d6 modified by CHA:

2d6	Result
2 or less	Hostile
3-5	Unfriendly
6-8	Neutral
9-11	Indifferent
12 or more	Helpful

Surprise

Keep it simple, the suprised side doesn't act, then initiative.

Initiative

There are two basic possibility: Group Initiative of NO Initiative! See later.

• Group Initiative [OSR]: both side roll d6, the group with the greater value starts the fight, if the rolls are equal, both group comes simultaneous (You can roll every turn). Every group member declare their action, than resolve it.
  Note: We use that because of the simplicity.
• Simultaneous initiative [PDM]: first ranged attacks and magic, then melee attacks. Professor Dungeon Master explains this method in this video. At simultaneous melee attacks, if a target dies, compare the attack values, and if the attack of the killed target is lower, it loses it's attack.

Combat

Everyone does one thing a turn by large. Examples:

• ATK/SPELLCHECK
• Go NEAR and ATK/SPELLCHECK
• Go RANGED
• DODGE (You are HARD to hit)
• DISENGAGE and go NEAR (you can let the players and the NPCs disengage freely if you want)
• etc.

Try to keep in simple and flowing, but let the players innovate. For example:

"I want to jump over the table and strike down on the orc."

"Alright, make an Acrobatics CHECK with the ROOM DC. If you succeed, ATK with EASY, if you fail, ATK with HARD."

Or:

"Can I spot any weakpoint on the beast?"

"Ofcourse, your archetype is Druid, so make an EASY Medicine CHECK. If you succeed, your ATK will be EASY for the encounter against that beast. If you fail, you can try next round again."

Turns and Continual Time [ICRPG]

Everyone does one thing a turn by large and every time frame is a Turn. Use the Continual Time rule of ICRP (page 17), so you will engage everyone and help shy players take actions.

Luck Dice! [DM Scotty]

Players can use them on any roll. I use the Luck Dice rules from DM Scotty with the following changes:

• You get a Luck Die after the second failed roll in a row, and for every fail after that
• You can have three Luck Dice maximum

Class-specific CRIT tables [DCC]

The funnest rule after Spells and Luck Dice! If a character rolls a natural 20, take your maximum DAM and roll from the table assigned to your class and level.

You can see my CRIT tables later in the Useful Tables section.

Optional: create for monsters also, or use the Lingering Injuries table from 5e DMG.

Fumble Table [DCC]

If a character rolls a natural 1, roll of the Fumble table deter-mined by your armor. You can see my Fumble table later in the Useful Tables section. You can use it for monsters also.

Armor Type	Fumble Die
No armor	d4
Light armor	d8
Heavy armor	d12

Death

Roll for Dying [ICRPG]

When you reach 0 HP, you go unconscious. Roll 1d4, after that many turn you die. Roll a d20 in every round, on a natural 20 you get up with 1 hp.

Injuries [FTD]

Make a table for injuries. When you are stabilized, roll from the table, and apply that injury to your character.

My example, inspired by FTD:

d20	Injury
1	A false hope, you're dead
2	Lose 1d6 Strength score
3	Lose 1d6 Dexterity score
4	Lose 1d6 Constitution score
5	Lose 1d6 Intelligence score
6	Lose 1d6 Wisdom score
7	Lose 1d6 Charisma score
8-13	Roll from the Lingering Injury table [5e DMG]
14-19	Disadvantage all CHECKs until rest
20	Instantly heal 1 HD

Optional: if a character gets knocked down two times in one encounter, make a CON SAVE against ROOM DC, if it fails, the character dies instantly.

When are you dead

• When you are bleeding out unconscious for 1d4 round
• When you roll natural 1 after getting stabilized
• When you are reduced to negative (3+LVL+CON)
• When any of your ability scores goes to 0

If you survive...Rest

• Short rest: spend one HD.
• Long rest: spend and regain all your HD.

A set of optional rules

Advantage and Disadvantage [5e]

Use instead or next to HARD and EASY. If the circumstances are so in favor of the character you can give both or you can give autosuccess to the attempt.

Contested CHECKS [OSR]

If two creature try to contest each other in a raw ability check (e.g. armwrestling, chasing, games etc.), you can use the "roll under" Ability check rules from most OSR systems.

Each side rolls, and whoever rolls highest without going over, wins. On a tie the side with the bigger Ability score wins. If both side fail, you can call a re-roll one turn later, or the creature who rolled closer to its Ability score wins.

Effort [ICRPG]

You can utilize the Effort rules from ICRPG.

My rule of thumb:

• Attempt DC is the ROOM DC
• The effort needed can be also the ROOM DC or arbitrary
• Without PROF: 1d4 + Ability modifier
• With PROF: 1d8 + Ability modifier

Moral

Keep it simple.

• For enemies I usually roll a 2d6 [OSE]. If I roll over the "Enemy moral", the enemies surrender. Enemy moral is usually half of the room DC (rounded down).

• For PCs I call for a WIS SAVE againts the ROOM DC.

Skill Challenges [4e]

One of the best rules in 4e. Set a DC, set a Success Treshold, and let the players be creative. Here is a video where Matt Colville explains it and here you can read some uses for it.

Timers! [ICRPG]

Roll 1d4. After that many turns, something awful happens!

Useful Tables - Classes and Spellchecks

Abilities and their modifiers

Lay on Hands

SPELLCHECK

DC	Success Level	Spell Dice
1	-	Mishapt
2-11	-	Failure
12-15	1	Base Effect (1d)
16-20	2	Base Effect + 1d
21-26	3	Base Effect + 3d
27-31	4	Base Effect + 6d
32-35	5	Base Effect + 10d
36 +	6	WONDER (DM Discreation)

What is the Spell Die? It can be:

• Effect and Duration: d4 (e.g. Shield: 1d4 AC, Bless: 1d4 ATK for 1d4 turns)
• Ranged damage: d6 (e.g. Firebolt: 1d6 fire DAM)
• Melee damage: d8 (e.g. Chill Touch: 1d8 cold DAM)
  
  

General Mishapt Table

d20	Mishapt
1	A random spell is cast (roll d6 for Success Level)
2-3	Caster falls PRONE, DEX SAVE
4-5	Caster becomes WEAK, STR SAVE
6-7	Caster is FRIGHTENED, WIS SAVE
8-9	Caster can’t attempt the spell until REST, INT SAVE
10-11	Caster can't target the same creature until REST
12-13	Caster becomes STUNNED, CON SAVE
14-15	Caster can't cast any spell until REST, CHA SAVE
16-17	The spell affects a random target
18-19	PC/Archetype-specific mishapt (DM discreation)
20	Backfires on the caster (roll d6 for Success Level)

Useful Tables - Crit and Fumble

Class-specific Crit Tables

Note: You can always use Luck Dice!

Crit Table for Fighters

Roll	Result
1	Inflict +1d10 DAM and 1d4 DAM to a random ally CLOSE to the target .
2	Inflict +1d8 DAM with this strike.
3	Inflict +1d8 DAM and enemy can't move next turn.
4	Inflict +1d8 DAM and knocks weapon into the air.
5	Inflict +1d8 DAM and the enemy is PRONE.
6	Make another ATK.
7	Inflict +1d10 DAM and enemy's ATK is HARD.
8	Inflict +1d10 DAM and sunders enemy's weapon. If he has no weapon, inflict 1d12 damage instead.
9	Inflict +1d10 DAM and enemy is EASY to hit.
10	Savage blow. Inflict +2d10 DAM with this strike.
11	Inflict +1d12 DAM and BLINDED for 1d4 round.
12	Inflict +1d12 DAM, the foe becomes PRONE and make another ATK.
13	Inflict +1d12 DAM, CON SAVE vs (DC 10+PC LVL), or become STUNNED for 1d4 rounds.
14	Inflict +1d12 DAM, the foe can't ATK next round.
15	Hammering blow. Inflict +2d12 DAM with this strike.
16	Inflict +2d8 DAM, CON SAVE vs (DC 10+PC LVL), or become PARALYSED for 1d4 rounds.
17	Inflict +2d8 DAM, the foe can't act next round.
18	Inflict +2d10 DAM and STUNNED for 1d4 rounds.
19	Inflict +2d10 DAM. If the target dies, ATK another enemy NEAR.
20	The target dies instantly if it has less HP than you. Else you inflicts 2d12 DAM.
21	Inflict +2d12 damage with this strike, and the foe must make a CON SAVE (DC 15 + PC LVL) or suffer PARALYSIS.
22	Foe loses 50% of current HP.
23	Inflict +3d8 DAM, the foe must make a CON save (DC 15 + PC LVL) or die in 1d4 rounds.
24	Inflict +3d10 DAM, the foe must make a CON (DC 10 + PC LVL) or die instantly.

Fumble Dice

Armor Type	Fumble Die
No armor	d4
Light armor	d8
Heavy armor	d12

Crit Table for Fighters

Roll	Result
25	Inflict +3d10 DAM, and the foe does nothing but wail in agony for 1d4 rounds.
26	Inflict +3d12 DAM, and the foe suffers permanent paralysis.
27	Inflict +3d12 DAM, and foe begins drowning in his own blood and expires in 1d4 rounds.
28+	Foe decapitated with a single strike. You are Death incarnate. Continue to make ATK against any foes NEAR until you miss.

Crit Table for Clerics

Roll	Result
1	Inflict +1d8 DAM and 1d4 DAM to a random ally CLOSE to the target.
2-3	Inflict +1d6 DAM with this strike.
4-5	Inflict +1d6 DAM and the enemy is PRONE.
6	Make another ATK.
7-8	Inflict +1d8 DAM.
9-10	Inflict +1d8 DAM and knocks weapon into the air.
11-12	Inflict +1d8 DAM and enemy can't move next turn.
13-14	Inflict +1d8 DAM and enemy is EASY to hit.
15	Savage blow. Inflict +2d8 DAM with this strike.
16-17	Inflict +1d8 DAM and sunders enemy's weapon. If he has no weapon, inflict 1d12 damage instead.
18-19	Inflict +1d8 DAM and enemy's ATK is HARD.
20	Inflict +1d10 DAM, CON SAVE vs (DC 10+PC LVL), or become STUNNED for 1d4 rounds.
21-22	Inflict +1d10 DAM, and foe can move only NEAR.
23-24	Inflict +1d10 DAM, and BLINDED for 1d4 round.
25	Inflict +1d10 DAM, the foe becomes PRONE and make another ATK.
26-27	Inflict +2d8 DAM, and the foe can't act next round.
28+	Inflict +2d8 DAM and STUNNED for 1d4 rounds.

Useful Tables - Crit and Fumble

Class-specific Crit Tables

Note: You can always use Luck Dice!

Crit Table for Rogues

Roll	Result
1-2	Inflict +1d6 DAM and ugly scar.
3	Inflict +1d6 DAM and foe can move only NEAR.
4	Inflict +1d6 DAM and foe can't move next turn.
5	Make another ATK.
6	Inflict +2d6 DAM.
7	Inflict +1d8 DAM and foe can't speak.
8	Inflict +1d8 DAM and foe is STUNNED for 1 round.
9	Inflict +1d8 DAM and foe is BLINDED for 1d4 rounds.
10	Inflict +1d8 DAM and foe is PRONE, and make another ATK.
11	Inflict +1d8 DAM and foe can't attack next turn.
12	Inflict +2d8 DAM.
13-14	Inflict +1d8 DAM, and enemy's ATK is HARD.
15	Inflict +1d8 DAM, and foe must make on a CON SAVE (DC 10+PC LVL) or faint from the pain.
16-17	Inflict +2d6 DAM, strike to head. Foe must make a CON SAVE (DC 10 + PC LVL) or fall unconscious.
18-19	Inflict +2d6 DAM, and foe can take only no action next turn.
20	Inflict +2d6 DAM with this strike, and the foe must make a CON SAVE (DC 10 + PC LVL) or die in 1d4 rounds.
21-22	Inflict +2d6 DAM with this strike, and the foe must make a CON SAVE (DC 10 + PC LVL) or fall unconscious from shock and massive blood loss.
23-24	Inflict +3d6 damage with this strike, and the foe must make a CON SAVE (DC 12 + PC level) or suffer paralysis.
25-26	Inflict +2d6 DAM, and foe must make a CON SAVE (DC 12 + PC LVL) or die in 1d4 rounds.
27	Inflict +2d6 DAM, and foe must make a CON SAVE (DC 12 + PC LVL) or die instantly.
28+	Inflict +3d6 DAM, and foe must make a CON SAVE (DC 12 + PC LVL) or die instantly.

Fumble Dice

Armor Type	Fumble Die
No armor	d4
Light armor	d8
Heavy armor	d12

Crit Table for 0-levels and Wizards

Roll	Result
1	Inflict +1d4 DAM.
2-3	Inflict +1d4 DAM and foe can move only NEAR.
4-5	Inflict +1d6 DAM and foe is last to act next turn.
6-7	Inflict +1d6 DAM
8-9	Make another ATK.
10-11	Inflict +1d6 DAM and knocks weapon into the air.
12-13	Inflict +1d6 DAM and enemy can't move next turn.
14-15	Inflict +1d6 DAM and the enemy is PRONE.
16-17	Inflict +1d8 DAM
18-19	Inflict +1d8 DAM and foe can't ATK next round.
20	Inflict +1d8 DAM, and foe must make a DC 15 CON SAVE or spend next round INCAPACITATED.
21-22	Inflict +1d8 DAM, and ATK again.
23-24	Inflict +2d6 DAM, and foe can't act next round.
25-26	Inflict +2d6 DAM, and BLINDED for 1d4 rounds.
27+	Inflict +2d6 DAM and STUNNED for next round.

Fumble Table

Roll	Result
1	You miss wildly but cause no other damage.
2	DC 10 DEX Save; if fail, spend next round PRONE.
3	Weapon comes loose. Your next ATK is HARD.
4	Your weapon is damaged
5	PRONE and must use an action to stand next round.
6	Weapon entangled and spend next turn untangling
7	You drop your weapon.
8	You accidentally smash your weapon
9	Next ATK against you is EASY.
10	Joints of armor seize up, can't move for 1d4 turn.
11	You ATK at one random ally within range.
12	You manage to hit yourself, taking normal DAM.

Useful Tables - Injuries and Equipment

Injuries Table

d20	Injury
1	A false hope, you're dead
2	Lose 1d6 Strength score
3	Lose 1d6 Dexterity score
4	Lose 1d6 Constitution score
5	Lose 1d6 Intelligence score
6	Lose 1d6 Wisdom score
7	Lose 1d6 Charisma score
8-13	Roll from the Lingering Injury table [5e DMG]
14-19	All CHECKs are HARD until rest
20	Instantly heal 1 HD

Lingering Injuries Table

d20	Injury
1	Shocking blow. CON SAVE or go unconscious.
2	Stunning blow. CON SAVE against being STUNNED for 1d4 rounds
3	One eye. Perception that rely on sight and ranged ATK are HARD. If no eyes left, you are BLINDED.
4-5	Foot. You can move only NEAR, and you must use a cane or crutch.S
6-7	Hand. You can use only one hand.
8-11	Torso. CON SAVE every turn. Fail: can't act on your turn because of internal pain.
12-13	Open wound. Lose 1 HP every round the wound persists.
14	Horrible Scar. Persuasion CHECKs are HARD, but Intimidation CHECKs are EASY.
15	Broken Weapon. Can't use weapon, until repaired (only magical weapon can break a magical item.)
16	Damaged Armor. -2 to AC, until repeared. If that brings the armor's AC to 0, then it breaks. (only magical weapon can break a magical item)
17-20	Minor Scar. Nothing.

Magic Items

• Effect, Duration or Charge: d4
• Ranged damage: d6
• Melee damage: d8