The Best RPG for Megadungeons and Casual Players

Good megadungeon play has to be brisk if you want to make any progress. Rules have to be easy if you want your ADHD players to get into them. Thus it was that I asked the players of my drop-in-drop-out (you are welcome to join the Discord) mega dungeon setting (a town between Stonehell, Tegel, and a mega-forest) to put aside their FAGE RPG PCs and start rolling new murderhobos. FAGE is fine… for another kind of campaign, but lemme tell you about Icosahedron Cult.

It’s basically one page of rules, one page of items, and a page of extraneous DM stuff. 

The central mechanic is that you roll a pure, unmodified d20. You just need to roll as high as the DM says. So simple.

You don’t get any of the traditional D&D ability scores, and your rolls aren’t modified by any scores anyways. Instead, there are stats like gregariousness, greed, insanity, and psionic potential. 

There are a dozen classes to keep it interesting, and everyone is given character making prompts so they play someone ostensibly interesting and unique.

The weapons are random, but damage is by-class, so we don’t spend all session shopping. Armor is also as per class. 

For magic, I went with a risk-reward freeform system. 

So I’mma put the current version of ISOC RPG below. You can visit the Google Doc if you want to keep up with changes I make as we go along playtesting some more. Also, two columns for printing ease on the doc.

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Icosahedron Cult

Try to do things. The GM calculates the odds based on your class, level, methods, and if Saturn is in retrograde, then asks for a number or higher to be rolled on a d20.

Armor Class makes it easy for the GM

The number to hit a monster or PC is its AC+situational difficulty. When running a published module, convert descending AC to ascending and cap all ACs at 20 (if you try to shoot Smaug or the Demogorgon, you’ll need to roll a 20 with disadvantage).

The AC for PCs is 10 plus Tough Rating. Raise AC by 1 per five levels gained if not a Wizard.

Name your weapons

All PCs start with some gear. You can carry three ready items and ten backpack items; fill empty slots with rations, bandages, or lamp oil on your first outing. They also have armor that is responsible for their TR-AC. The armor has to be taken off to sleep or be sexy effectively.

Damage is class-based rather than weapon-based

If you hit with a weapon, deal damage equal to a roll of your class’s HD. If you crit (hit w/nat20 or LKYN, you deal an extra d30 damage.

Classes (you can choose after seeing your gear)

1. Fighter: d12 HD, 5TR. Gets to roll d24s instead of d20s when attacking, and 21~24 count as a 20.

2. Dungeoneer: d8 HD, 3TR. Basically a thief, so they have much better odds with locks and such. They know the Dao of dungeons and Gygaxian Naturalism.

3. Dwarf: d12 HD, 6TR. Autistically insist that they can smell gold and sense sloping passages.

4. Wizard: d6 HD, 0TR. Can risk HP to cast spells.

5. Elf: d7 HD, 2TR. Can cast aspersions. Great at bushcraft. Walks on snow. Sees far in daylight.

6. Catman: d8 HD, 3TR. Great reflexes and eyes. Amazing fashion sense.

7. Dogman: d9 HD, 2TR. Good at smelling and hearing. Needs walkies at dawn.

8. Half-succubus: d7 HD 1TR. Very good at seduction, but keeps fellow PCs in the friend zone. Learn one spell per wizard seduced.

9. Idolator: d7 HD, 2TR. Can ask their patron deities for miracles, racks up DCCish Deity Disapproval.

10. Half Orc Barbarian: d14 HD, 0TR. Has no patience to listen at doors. “LET’S GO! YAWP!"

11. Loathsome Gerblin: d6HD, 4TR. Okay at skulking.

12. Monk: d6HD, 5TR. Other PCs have harder rolls for unarmed or improvised weapon attacks, but not monks. Armed monks are cool too.

Name Your Spells

When you cast a spell, describe the desired effect to the GM and get your difficulty target. If you fail to cast a spell, take damage equal to the amount you failed by. If this knocks you to zero, you don’t die, but probably will if you take any further damage.

Six Scores (roll 3d6 for each one)

1. Lucky number: If you roll exactly this number when passing a check, you do a crit. LKYN score can be burned down to reach a crit range, or to change a die rolled by, for, or against you in your favor by an equivalent amount. Burn is permanent and a low LKYN is less useful, but you may get Luck rewards for being excellent, dudes or carousing.

2. Plot Armor: This number is the minimum HP you start with. Roll your HD at character gen and have that many HP or the plot armor number, whichever is higher. 

3. Gregariousness: Purely a roleplaying suggestion in stat form. Has no bearing on checks in and of itself.

4. Greed: as per GREG.

5. Insanity: A stat that raises when you see or do crazy things and fail to cope. If it reaches 20, you go AWOL-NPC.

6. Psionic Potential: Chance on a d100 that you are special and then the GM groans and adds rules for psionics to this game.

Finishing touches that you can get around to

Pick a former career. Decide how you know another PC in the party. Decide something that pisses you off and something you fear. Name a regret and an aspiration.

 

Title each level you gain; it’s an accomplishment

The surviving PCs should level up every once in a while, and maybe gain some luck too. Each level gained lets you roll your class HD and gain that many HP. After level five, you only gain TR in HP per level. After lvl 10, no more HP gains. 

You can survive beyond 0HP–albeit unconscious, slowly dying, and vulnerable–up to negative HP equal to your level.

Healing and comfort eating

Roll your HD with each ration spent to regain that many lost HP. At dawn, if you slept 6 hours, had breakfast, and shared a bit of backstory, you get lvl×HD rolls of HP back. 

Monsters and Combat

Do crits only on a 20 (no lucky number unless a well statted NPC), which are usually just horrible things instead of the d30 extra damage that PCs use.

Unless monsters surprise the PCs, the PC attackers go first. Have attacks checked before spells are cast. Monsters get a chance to hurt a spellcaster before the spells go off, in which case it can’t be cast that round, so keep those wizards protected!

GEAR

Warrior types (one of these d6):

1. Sword (d10 subtable):

1. Katana edgelord

2. Zweihander

3. Browdsowd

4. Gladius

5. Short sword

6. Falchion

7. Scimitar

8. Sabre

9. Sword-cane

10. Double sword

2. Ax (d5)

1. Bearded

2. Throwing

3. Broadaxe

4. Sickle

5. Adze

3. Smasher (d10):

1. War hammer

2. Mace

3. Club

4. Morningstar 

5. Cudgel

6. Flail

7. Mitre

8. Crowbar

9. Quarterstaff

10. Nunchaku

4. Polearm (d5):

1. Poleaxe

2. Halberd

3. Pike

4. Scythe

5. Billhook

5. Brass knuckles

6. Spear (d6)

1. Trident

2. Bident

3. Pitchfork

4. Spear spear

5. Quiang

6. Javelin

Priest types (d3):

1. As per warrior (roll on their table), but base your god on the weapon.

2. Whip

3. Giant Cross

Granola types (d8):

1. Falcon 

2. Bow

3. Doge

4. Longbow

5. Sling

6. Bola

7. Boomerang 

Spirits
Mage types weapon is a (d10):

1. Cultist dagger

2. Staff

3. Caduceus

4. Imp (like a falcon)

5. Psychokinesis

6. Evil eye, bad luck (foe bonks into walls and stuff)

7. Heavy tome

8. Pew pew wand

9. Just a gun

10. Sparkly fingers

Thief types (d10):

1. Dagger (d5):

1. Sax

2. Stiletto

3. Dirk

4. Main gauche & short sword

5. Kris

2. Blackjack

3. Blowgun

4. Garrote

5. Rapier

6. Flintlock

7. Ninja star

8. Straight razor

9. Crossbow 

10. Kabong

D12 additional gear:

1. A dutch oven, a frypan, some garlic bulbs, a bedroll, a voodoo doll, a cane, 20’ hempen rope, reading lamp, and a dictionary

2. A bedroll, an area guide complete with restaurant reviews, some small scissors, a dagger, a comb, a long flute, and an ass

3. A little, indentured servant; a book of fantastical voyage accounts; four small daggers; spidersilk cloak, and a matryoshka doll-set

4. Mom’s sword, 10’ chain, a box of mummy-dust, a mirror, a bone-straw, a letter from a lost-love

5. A wool cloak, a bedroll, straw shoes, flint and tinder, and a celt (stone ax)

6. Some incense cones (six aromas), a shaving blade, a large, straw hat, a felt mat, a book of sutras

7. d3 holy statuettes, a whiskey flask, a jar of glow-worms, a walking-stick, a pamphlet of sensual-massage techniques, a hand-puppet, and a linen blanket

8. A necklace of ears, a macuahuitl, white face-paint, three wigs,20’ rope, a lantern, a handcart as long as a tall man

9. A looking-glass, a book of constellations, a jar of space-slugs, a stiletto, a ruff, pantaloons, and a leather blanket

10. A hand mirror, some prayer-beads, a treasure map, a giant wrench, thirteen porcelain doll heads is a sack, 20’ rope, and two blankets

11. A chess set, some bandages, a bow, a quill full of arrows, a lamp, 20’ rope, a foppish hat, a shepherd's dog, and a chastity belt

12. A sling, seven blessed sling stones, the bronze skull of Dungid-kin in a sack, a tattooing-kit, a wicker fish-trap, LKYN feet of rope, a fleece.

This page is just to help the GM

Chance and its difficulty number

Slim chance in hell

1~4% 20 despite disadvantage

5%: 20

6~10%: 19+

11~15%: 18+

Unlikely

16~20%: 17+

21~25%: 16+

26~30%: 15+

31~35%: 14+

36~40%: 13+

Okay sure

41~45%: 12+

46 ~50%: 11+

51~55%: 10+

Likely

56~60%: 9+

61~65%: 8+

66~70%: 7+

71~75%: 6+

Cakewalk

76~80%: 5+

81~85%: 4+

86~90%: 3+

91~95%: 2+

Don’t need to roll

96~100% 

Spell considerations

Base            10-[½LVL]

Pure utility        -5

Target has higher

HD than caster        +1/5HD imbalance

d4 dmg            +0

d6 dmg            +1

d8 dmg            +2

d10 dmg        +4

d12 dmg        +6

d20 dmg        +10

Multiple targets        +Total HD 

they have 

collectively 

more than 

the caster

Duration 10 mins    +0

An hour        +1

Days            +3

Year and a day        +5

Permanent        +7

Slow spell/ritual    -3

Valuable reagents used    -1~-5

Luck Rewards

PCs were heroes    +1LKYN

PCs had heavy losses    +d3LKYN

PCs stopped a big bad    +d10LKYN

Carousing Table

PC player individually decide what die to roll from a d4 to a d30; great risk=potential Luck reward. We’re gonna repurpose my Montage Table for the good and bad results.

• 1~5: d3 Luck gain, and an adventure rumor.

• 6~12: d6 Luck gain, roll on the good Montage Table results.

• 13~15: d8 Luck gain, roll on the good results.

• 16~22: d10 Luck gain, roll on the bad results.

• 23~29: d12 Luck gain, roll on the bad results.

• 30: d14 Luck gain, roll on the bad results.

  
  

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