AIMHack - A Primer

Back in 2009, some friends over at the Spiderweb Software forums and I had a problem. We wanted to run some sort of tabletop RPG campaign over AIM, and initially our plan was to use 4th edition D&D. Unfortunately, almost none of the prospective players actually owned the books. After a lot of discussion, we decided that we needed our own system and our own setting. Nothing super-complicated, just enough to get rolling (heh) and tell some fun stories.

Well, one 3am session of brainstorming later, I had crafted the beginnings of a simple d20 system that was geared towards playing on IM clients. Again, the main word here is "simple," particularly as I look back after having moved on to more complicated systems. But anyway... many years later, the system has been used for numerous full campaigns, and I have to say I'm pleased with the results. In fact, the system outlived my own involvement with it... former players continued to host their own games long after I had run my last, many continuing to use AIMhack's canonical setting. 

A medium such as AIM allows the DM to handle things a little differently from a face-to-face game. For instance, if only one party member rolls high enough to see the goblin before it ducks behind the corner, the DM can simply alert that player in a private channel. And if one party member decides to dive down into the water and fight the dire octopus, they can do so in a private IM to leave the rest of the party in suspense. Also, that did happen once. It worked about as well as you'd think.

Of course, there's a downside to the medium. I've found that most people are less likely to commit to a full-length session. Thankfully this can be mitigated by a few helpful spectators, if they are willing to take over for absent players. In the first session I adjudicated, we wound up using 9 people to control 5 characters over the course of the night. And it worked just fine.

Game Logs

Perhaps the best thing about running games over an IM client is that you have a very easily-accessed log of the game. Players who missed a session can catch up, and interested spectators can even read the thing like a novel if they wish. And of course, the DMs running the game can go back and use past events to inform their future plans.

Test Runs

  • 9-4-09 - Coco Liebwitz vs the Lizards

The Labyrinth Campaign (Complete!)

The Mote Campaigns

The System

It's not exactly rocket science, and I'm constantly working to keep it that way. Roll a twenty-sided die (a d20), and then add any bonuses. That number is opposed to a check (set by the DM, who is running the game). If you roll above the check, you succeed. If you don't, you fail. If you roll a 1, very bad things happen. If you roll a 20, very good things happen.

Of course, the dice aren't everything. Not everything needs to be resolved with a roll, and sometimes it's a lot more fun when it isn't. Justifying things with good roleplaying is paramount to success... what you actually say to the duke is far more important than the 6 you have in Diplomacy. Sometimes, a good enough explanation will make an actual roll completely unnecessary.


There are six main attributes. The first three will influence a wide variety of rolls.

  • Strength: Hit things hard, endure damage, lift heavy things. Affects your skills in melee combat.
  • Dexterity: Hit things from a distance, dodge blows, be a ninja. Affects your skills in ranged combat.
  • Intelligence: Hit things with magic, resist illusions, solve puzzles. Affects your magic skills.

The other three attributes don't actually determine rolls, but are still very important.

  • Hit points: Health. Run out and you start bleeding out, losing Stamina. Get to 0 HP and 0 Stamina, you die.
  • Speed: How fast you can move in one turn. Normally this is only relevant in combat.
  • Stamina: Represents fatigue. Spend a point to expend extra effort on something.


The basic version of AIMhack has 13 skills for characters to use. The number of points you have in a skill is equal to the bonus you get on rolls involving that skill. So if you have a 6 in Bluff, all rolls you make for bluffing will get a +6 bonus (not counting any other bonuses you might have).

Some skills also get a bonus from an attribute, and those skills list the attribute in parentheses. For example, making an Artifice roll also lets you add your Intelligence attribute.

  • Artifice: Knowledge of engineering, crafting, traps and such. (Intelligence)
  • Composure: Keep your cool when bluffing and/or negotiating.
  • Crafting: Making things, whether it's alchemy, weaponry, houses, you name it. (Intelligence)
  • First Aid: Anatomy and other healing lore. Helps determine how much HP/Stamina is recovered by resting. (Intelligence)
  • History: Knowledge of all things historical and political. (Intelligence)
  • Magic: Magical lore, and spellcasting ability. Must pick a specific school of magic. (Intelligence)
  • Martial: Fighting skill. Pick a weapon or style of fighting, and flail away. Train in individual weapons separately. (Strength or Dexterity)
  • Nature: Knowledge of all things natural, animal, vegetable, and mineral. (Intelligence)
  • Perception: Sharp eyes, sharp ears, sharp... nose?
  • Religion: Knowledge of all things religious. Normally specific to one pantheon. (Intelligence)
  • Stealth: Avoid being seen. Be sneaky! (Dexterity)
  • Streetwise: Gather information quickly, and know your way around town.
  • Thievery: Pick pockets, disable traps, do sleight-of-hand tricks. (Dexterity)


Attack rolls are simple. Roll 1d20 (that's one twenty-sided die), and add that weapon's skill. If you beat the enemy's defense score, you hit.

Defenses are just as simple as attacks. Characters defend themselves using each of their attributes, depending on what they're trying to avoid. But generally speaking, a character's defense is equal to 10 + the relevant attribute + any other bonuses.

Some examples of attacking and defending include:

 Attack Roll
Attacking with a sword
 1d20 + Martial (Swords) + Strength
 10 + target's Dexterity + armor bonuses
Shooting a bow
 1d20 + Martial (Bows) + Dexterity
 10 + target's Dexterity + armor bonuses
Launching a fireball
 1d20 + Magic (Evocation) + Intelligence
 10 + target's Strength
Casting a charm spell
 1d20 + Magic (Enchantment) + Intelligence
 10 + target's Intelligence + target's Magic (Enchantment)


You start with ten stamina. If you ever run out, you're rendered useless in combat and typically go unconscious. Strenuous activity is impossible, at any rate. But aside from being an indicator of health, players may spend stamina points to get a bonus on any roll, the size of which will vary from situation to situation. Expanding the effect of a spell, delivering a staggering bludgeoning, running really really fast, etcetera. Also, non-standard actions could cost stamina (regular attacks and actions never do), at the DM's discretion.

Stamina normally refills after a rest, or it could be restored by potions.

Character Creation

These are the basics for making characters at level 1, the starting point for any new player.


When you start, your Strength, Dexterity, and Intelligence must add up to 10. No score can be zero, nor can it be negative. Also, characters with less than 2 points in an attribute are severely limited in some way (an Intelligence of 1, for example, is no smarter than a mountain goat).

Stamina always starts at 10, and Speed always starts at 5. Your starting HP is 10 + your Strength score.


Your skills all start at 0, like an average peasant. You get 20 points to spend. To move a skill up to 1, spend one point. To move it up to 2, spend two more points, and so on. So, to take a skill from level 0 to level 4, spend 10 points total (1+2+3+4). Do this until you run out of points, and negotiate with the DM about what to do with any leftovers.

You can train in any skills you want, but it's good to give yourself some way of defending yourself no matter what. This could be as simple as putting a point in Martial (Daggers), just so that your fireball-slinging wizard has a backup plan when he runs out of Stamina.


Casting spells is a tricky enterprise. If your character wants to cast spells, they first need to train in the Magic skill. Whenever you train in Magic, you have to pick a school of magic, which determines what kind of spells you can control. The schools of magic are as follows:

  • Abjuration: Protective spells and countercharms.
  • Conjuration: Summoning creatures and materials, also including healing magic.
  • Divination: Spells that reveal information.
  • Enchantment: Charms, illusions and other mind-affecting spells.
  • Evocation: Manipulating raw energy, creating something from nothing.
  • Vitaemancy: Manipulate and destroy life-force, also including most necromancy.
  • Transmutation: Transforming and enhancing objects on a fundamental level.

Bear in mind, a character can train in multiple schools of magic, the skills are just tracked separately. So a wizard could be moderately skilled at creating illusions, with a 5 in Magic (Enchantment), and still be able to throw a fireball or two around, with a 2 in Magic (Evocation).

As for spells themselves, a spellcaster can only keep so many in their head at once. Until a mage can sit down for a few hours and study their spells, they can only hold a number of spells equal to their Intelligence score. Unless specified, a spell isn't "used up" upon casting, so a player with 4 Intelligence can prepare four spells and use them repeatedly over the course of a day. Then, they can take a few hours and swap them out for new spells the next day.

There is an existing compendium of (nearly) all the spells ever used in an AIMhack campaign, right here --- AIMhack Spell Compendium. Use it as a guide for coming up with your own spells!

Character Advancement

Every so often, your characters are bound to do something worthy of reward, and you'll level up. When this happens, your skills and attributes can increase. Exact methods for leveling up have varied based on the campaign, but the original method works like this:

  1. Increase one Ability (Strength/Dexterity/Intelligence) by 1.
  2. Increase your Hit Points by your Strength score.
  3. Gain a number of skill points determined by your DM.
  4. Spent those points to increase your skills, as during character creation.


Of course, character progression involves more than just basic stat-grinding. Occasionally, your character will do something so insane, so noteworthy, so epic, that your character will gain what is called a "perk". These are bonuses for your character, usually tailor-made by your DM. Here are some examples from actual games I've run:

  • Burning the Candle at Both Ends - Whenever you spend your last stamina point on an attack, you score an automatic critical hit.
  • Glimpse of Infinity - Your character can sense nearby portals. Also, whenever your character rolls a natural 20, you are haunted by strange visions, whose cryptic meaning gives you a small bonus on your next roll.
  • Happy Misanthrope - Gain +2 to Intimidate versus humanoids, -2 to Diplomacy versus humanoids. Reverse these values when dealing with non-humanoids.
  • Calm Under Pressure - +2 to all non-Martial, non-Magic skill checks while in combat.
  • Seize the Advantage - +4 to attack rolls when the enemy does not see you coming.
  • Reckless Abandon - When you have less than half your maximum Hit Points remaining, you gain a +1 bonus to all rolls.
  • Momentum - When you land a successful melee attack, you gain a +1 bonus to all defenses until your next turn. If you land a second successful melee attack that turn, the bonus increases to +2.

Sample Starting Characters

Name: Phil Darkbrooder
Occupation: Necromancer
Race: Human
Alignment: Whiny

Strength: 2
Dexterity: 3
Intelligence: 5
HP: 10

Magic (Necromancy): 4
Composure: 2
Stealth: 2
First Aid: 2
Perception: 1

Name: Thok
Occupation: Thok hit things
Race: Orc
Alignment: Hungry

Strength: 6
Dexterity: 3
Intelligence: 1
HP: 10

Martial (Whatever's nearby): 5
Streetwise: 2
Nature: 1
Perception: 1

Name: Sneaky Tim
Occupation: "None of your business"
Race: "What of it?"
Alignment: Pragmatic

Strength: 2
Dexterity: 5
Intelligence: 3
HP: 10

Martial (Dagger): 3
Stealth: 3
Thievery: 3
Composure: 1
Magic (Illusions): 1

Name: Lord Elfgracestein
Occupation: Obligatory Healer
Race: Obligatory Elf
Alignment: Reluctant

Strength: 2
Dexterity: 3
Intelligence: 5 
HP: 10

Martial (Obligatory Bow): 2
Magic (Obligatory Healing): 4
First Aid: 3
Religion: 1


Just to be perfectly clear, I am not intending to ever profit from this. I don't intend to publish it either. It's just an experiment, and a system that myself and my friends can use. Given that I'm taking a fair amount of inspiration from such classics as Dungeons & Dragons, I am well aware that I really couldn't sell it even if I wanted to. And I'm just fine with that.