Maze Rats as Micro-OSR

Written while listening to the Trine Soundtracks by Ari Pulkkinen and the Ori soundtracks by Gareth Coker

Choosing which glistening treasures to keep and which to leave behind. Clambering up slick rocks in hopes of not plunging into freezing depths below. Outsmarting Orc tribes through means of trading and trickery. Casting mysterious spells with wondrous and unpredictable effects in the torchlight of a dark dungeon. Picking loot off of your comrade’s quickly slaughtered body. Becoming more powerful and chiseled with every encounter, enemy, and environment. Relying on your cleverly constructed plans over the fate of a die roll.

These are all examples of experiences that OSR games specialize in; Resource Management, Dangerous Exploration, and Powerful abilities accompanied by the threat of death. Many systems are designed to produce these experiences, and a few of them are rules-lite and easy to print out at home. Among the smallest of these is Maze Rats, and man do I love it.

In October, the game Maze Rats by Ben Milton is hitting its 10th Anniversary. Within the last few years, Ben’s follow-up game Knave has taken the spotlight, mainly because it’s a skeleton of a system that can run TSR era modules with very little conversion. Because of this, Maze Rats has fallen into a comfortable niche of people finding it, playing it, and moving on after finding heavier systems.

But I am no such person.

I first started using Maze Rats for the helpful amount of tables provided; easy d66 tables for nearly everything I would need for a game, without an overabundance of filler content. The Maze Rats booklet had a place in my GM bag ever since I first printed it out, but it took me a little longer before I eventually played the system included in it.

After playing a short few sessions with it, my players and I switched to an Oddlike with more familiar mechanics and less lethality, but I myself kept thinking about Maze Rats whenever I wasn’t running games. It was simple, and I was curious why it worked well. With enough thinking, I believe I realized why. This realization has made me jump back into running the system, and having an absolute blast with it, to the point of it suddenly becoming one of my favorite TTRPGs in general.

The reason Maze Rats works so well for me is because it essentially became a tiny, micro game capable of emulating and producing classic OSR gameplay elements and encounters. Old School games are often designed to challenge the players and create difficult choices, and Maze Rats is a shining example of this thesis done simply. This is done in a few key ways, and some more subtle ones that just delight me, hidden in the booklet.

The 0-4 Scale

To me, this is the heart of Maze Rats. It makes this game tick. All of the numbers that Maze Rats uses are small, and you’ll rarely ever see a number higher than 12. The dice used in the game are strictly d6s, the most common (and in my opinion, underrated) die. This keeps things familiar to new players and easy to access.

 There are only three main Ability scores, taken from Into the Odd: Strength, Dexterity, and Will. Anyone familiar with these words on their own will easily understand their use in this game. Ability scores will only ever be from 0 to 4, even for monsters. A PC will be able to increase an Ability score once every other level, for a maximum of 6 points total distributed in their stats by the 7th level. That hard limit, paired with the choice of using 2d6 for most rolls, and a constant Target Number of 10, means that a +1 and a +4 will give you wildly different chances of success. For example, trying to hit a 10 or higher with a +1 has around a 27% chance of success, while a +4 will have 72%. By keeping all of the numbers small, even one added bonus becomes incredibly valuable.

Danger Rolls here are trying to hit a target number of 10 or higher, as mentioned previously. This takes some mental load off of the Referee, as most systems with fixed Target Numbers do. This also provides players with a clear understanding of their chances of success, putting that decision in their own hands. Only rolling to avoid risk is present in Maze Rats as much as it is in any system with Saving Throws.

This 0-4 scale also applies to armor and combat mechanics. Base armor is 6, and the highest a monster may ever have is 10. Rather than adding Strength to hit, there is an entirely separate stat for combat, called Attack Bonus. Separating the attack modifier from the ability score really helps hammer in the concept of competent fighters who may be more smart than strong, a concept rarely leaned into in TTRPGs. More about “classes” to follow. The differentiation between unarmed, light weapons, and heavy weapons is a -1 or +1 damage respectively. That reminds me a lot of Original DnD if you ask me, and reaffirms the idea of meaningful numbers.

Advantage is present here, simply being to roll 3d6 and take the two highest. The chances of success, however, are increased immensely. Rolling 2d6 and trying to get a 10 has a roughly 17% chance, but if you have Advantage applied to that roll, suddenly that percentage jumps to a 35%, doubling your chances for success. The math gets more impressive with bonuses applied, all the way up to 89% with a +4 ability. The little addition of Advantage provides so much mechanical progression that it cannot be understated. This helps Levelling feel increasingly meaningful, as explored later.

Even the starting health is a mere 4 points. Taking just 2 points of damage will see a Level 1 character taken to half their HP. Small numbers mean that any number at all makes a huge difference. This produces a tried and true OSR principle, which I am lifting from Mausritter for the sake of excellence: “Dice are dangerous, Clever plans don't require rolls”. By setting up 1st level characters at an essential disadvantage, the gameplay is automatically oriented towards clever planning over lucky rolling. That lends itself to another OSR saying, “the answer is not on your character sheet”, although I myself partially disagree, since much of my games include puzzle solving through spells or items found along the way.

Familiar Territory

Common Dungeons and Dragons elements are present here, with smaller numbers to replace paragraphs of explanation. Rolling to Hit is here, cleverly combining the damage roll together. Morale and NPC Reactions tables are also represented with simplicity and ease. Danger Rolls are kept as rolling high over the target number, meaning players will cheer when they see double sixes. Sometimes a roll-under system turns away folks looking for an “authentic” DnD experience. Magic is here, thievery is possible, and combat is deadly. There are rules for healing and the levels here are meaningful. Maze Rats has all the trappings of what people sometimes expect from DND games, and to someone without any experience in the hobby at all, I am more than confident that these simplified versions of famous concepts are enough to provide the experience people are expecting.

Levels and “Classes”

The leveling system in Maze Rats is kept similarly small, easy to digest, yet has a few meaningful decisions that leave a big impact on a character’s progression. There are 7 levels in Maze Rats, with each one adding 2 to the maximum HP, and with every other level offering a different choice for the players to make. That choice is either going to be increasing an Ability Score by 1 (granting a much higher chance of success) or choosing a Feature listed from the character creation.

Features fit perfectly into the classic “Fighter, Magic-User, Thief” archetypes while offering subtle and effective gameplay changes and just enough customization for characters to earn their originality. Players can choose to add to their Attack Bonus (up to +4 by Level 7, making them a killing machine), they may receive another Chaos Spellslot (to be cast and forgotten once per day), or be granted a Thief Path, with each of the four path types adding Advantage to related sneaky activities. Paired with the importance of a +1 increase and Advantage, these decisions vastly change chances of success and what a player might deem “riskable” for further adventures.

Level 7 characters are going to feel mechanically powerful, and will hopefully have a huge supply of treasures to show from all of their experience. This produces what I hope is a similar feeling to surviving into the higher levels of other OSR games, with a still-present risk of death, but powerful tools to avoid it.

XP is gained through a simple series of session-related questions, and rewards players for attendance and trying risky activities over strict gold accumulation or monster hunting. The questions are vague enough to allow a Referee to make fair callings on the spot. Simply, if a player shows up to the game, they get at least 1 XP. If they overcame a difficult challenge, they get 2 instead. This could be escaping a dungeon with treasure to show for it, or some other simple objective that the Referee previously thought possible. The players receive a total of 3 XP if they overcome an impressive challenge beyond their expected ability. XP accumulates between levels, and certain amounts grant new levels. It will take 42 XP to get to level 7, which means either 42 boring sessions, 21 common sessions, or 14 high-risk sessions. Really, I assume it might take anywhere between 15-20 sessions to reach the highest levels in Maze Rats, leading to that micro feeling while still facilitating the power-creep that features in games with higher level caps.

Side Note: A good Referee paired with some good players should understand that a mechanical level cap should never mean that the campaign can’t continue past it. Progression after level 7 in Maze Rats ought to then be tied to in-world advancement, similar to Cairn and Electric Bastionland.

Compatibility and Accessibility

A huge draw to the OSR playstyle is system compatibility. Players and Referees don't want to spend too much time converting one awesome adventure into a different system with different design philosophies. A supposed downside to Maze Rats is the sharp change from d20 based system coherence, to 2d6 math. Yet with such simple numerical values, it becomes trivial to convert monsters into Maze Rats notation. The booklet itself helps list each of the different values a monster might have in terms of power level, making it easy to narratively convert anything from a similar OSR system. Since there are only a few numbers to worry about, it can be done on the fly with ease.

Converting Keep on the Borderlands, a DCC module, or any Cairn adventure is going to be quick and effective, ensuring that the players will be getting a similar experience to the original with just a little less math. The hardest part I’ve found when converting is traps and damage values, but usually that falls under a “Save or take 1d6 damage” or sometimes even 2d6 if it is especially deadly, taken that 12 damage could wipe out most characters.

Maze Rats was also designed with accessibility and speed in mind. Players don't need to understand how a TTRPG game is played when they first play Maze Rats, and character creation is so simple and requires very few decisions, that a player can have a handful of characters rolled up within 10 minutes. This is handy, because OSR games often pride themselves in the deadliness of their systems. Maze Rats is no exception, and actually can be more deadly than most other systems I’ve played so far. I have my own little Mortality rule to make death less frequent early on, mentioned later.

Just Enough Flavor, Hidden Rules Throughout

Most games come with a built-in setting, almost an expectation for the kind of world that works best with the rules and flavors. While most things fall into a generic Fantasy genre, there are still some elements hidden in Maze Rats that give the assumed world its own flavor. These can be found most notably in the Player Background tables, which features numerous pasts like Kidnapper, Housebreaker, Chimney Sweep, and even Slave. Rolling up a character means rolling up some scummy folks with challenging pasts, which happens to make jumping into adventuring that much easier. The author also writes that the world ought to be kept to humans and rare humanoid kin, which helps the odd and unnatural creatures that the players encounter stand out from the usual folk. Pair all that with the chaos magic, which sees players learning random two-word spells each day, and the world of Maze Rats finds itself with some clever character and charm without having a history or even a lore paragraph to explain the world.

Hidden amongst the tables are some great pieces of advice and rules, as well. A table for Mutations and Insanities implies that spells can go wrong, and may have permanent consequences. A blurb under the Monster Features table reminds Referees to make monsters harvestable, and the Monsters Abilities instructs to give players clues before the monster is seen. There is a Carousing table, and a rule to go along with it, but it isn't anywhere near the Rules of the game in the front. Hidden in the tables and texts are advice for finding information from Books, foraging different plants, some light alchemy rules, and trap styles and advice. That might not have a direct OSR comparison, I just think it’s really cool that Ben hid all kinds of stuff in the tables throughout.

OSR Advice

Perhaps my favorite part of Maze Rats, even more so than the tables, is the succinct advice given at the end of the booklet. Here Ben displays his incredible wealth of what makes OSR games tick, and gives instruction on how to prep sessions, run the game, and design the world in ways that will be familiar to anyone who has spent time in this hobby. These blurbs and bullet points are filled to the brim with actionable material and inspirational design ideas that can help conquer writers block and direct Referees to gameable content. And in perfect Ben Milton fashion, the advice here contains some guidelines for dungeon crawling procedures and hexcrawling rules, and it is presented as helpful advice for if the Referee chooses to include those elements in their game.

Optional Rules I’ve Used

In my time with Maze Rats, I’ve adopted a few house rules that amplify the game and help me achieve my perfect table experience. Inspired by Dreaming Dragonslayer, I’ve limited my players to 3 Bulky items and a reasonable amount of normal ones, to keep touch decisions as a constant without getting too bogged down with slots. To make the game less immediately lethal I’ve added Mortality, which is a stat that starts at 1. Whenever a player reaches 0 HP, they make a Mortality roll by rolling a d6 and trying to get above their Mortality. If they succeed, they gain a scar related to the damage dealt to them, they are bleeding out until stabilized, and their Mortality gets increased by 1. If they fail the roll, their character dies. This makes it so that dying early on is less likely, but as characters become more chiseled and scarred, they are faced with a higher and higher chance of death. Lastly, I’ve added Spell Tomes from Mausritter or Cairn—Bulky items that contain a single spell that can be cast once per day. There’s probably some more ways to integrate spellbooks into Maze Rats’ already excellent magic system, but this one does its job for now.

Conclusion

Maze Rats is amazing. It’s so elegant, and so simple, and so effective in its endeavors as an OSR primer. It’s a system I can sit with, stew on, and really get to know over time. Ben Milton took the OSR gameplay styles and expectations and found a way to get to those experiences quickly, while still maintaining an easy rule system with the necessary amount of depth. It has become my go-to system for new players, and may overtake some other Oddlikes when it comes to delivering a classic experience in as little fuss as possible. Sadly, Maze Rats is in such a niche of a niche hobby, that it is often overlooked by people searching for the ideal Fantasy experience. Because of that, I would like to list some resources for Maze Rats content, theory, and games that have similar structure. My hope is to keep the love for this game going and possibly add some more content for it in the next few years.

Resources:

Dreaming Dragonslayer, my biggest inspiration, with wonderful blogs and thoughtful writings: https://dreamingdragonslayer.wordpress.com/tag/maze-rats/

Conversion notes for OSR bestiaries:

https://lichvanwinkle.blogspot.com/2026/05/maze-rats-conversion-for-skerples.html

Similar game system by the guy that made Barrow of the Elf King:

FAR: https://natetreme.itch.io/far

Listening to a Vanished God, a Maze Rats coded Campaign:

https://tibbiusgames.itch.io/litavag

Principia Apocraphya, guidelines for OSR style games written by Ben Milton and Friends:

https://friendorfoe.com/d/Old%20School%20Principia-Apocrypha%20Mobile.pdf