Your TTRPG Design Principles?


He'll flip ya...Flip ya for real...
I don't know how multi-quote works on these boards; if I did, I could pick and choose about a dozen principles from the above 8 posts to make my own list - I think every one of you has something I'd fully endorse, and you each also hit something I'd not want to use. :)

So, cribbing from the above posts in some cases:

--- character generation has to be simple. 15 minutes, tops, to get it table-playable; fine-tuned details can be filled in later.
--- character generation involves a moderate-to-high degree of randomness, players should be encouraged to come up with character concepts after seeing what the dice say, not before.
--- character options (playable classes, species, etc.) need to be clearly laid out, along with the relative benefits and drawbacks of each.
--- gating some of those options behind roll requirements etc. to enforce rarity is acceptable
--- general principle: no benefit without an associated drawback, and vice-versa.
--- exceprience and-or advancement is a reward for what the character does, not the player
--- no metacurrencies (e.g. 5e's inspiration, luck, etc.) that allow a player to overrule or retry a die roll after the result of the first roll is known
--- the magic system should be powerful, but sometimes have risks attached both for the caster and anyone nearby (hat-tip @pogre )
--- players should as much as possible approach any challenge by thinking what a person in that situation might plausibly do. (hat-tip @Yora )
--- get modular. Taking a rule out [or changing or adding a rule] shouldn't cripple other parts of the game. (hat-tip @GMMichael )
--- even if there's a best-playable or "sweet spot" range of character levels, make the design open-ended; i.e. no hard cap on level or progession.
--- design the zero end of the game as well as the hero end and let each table decide what part(s) of that they want to play.
--- PCs and NPCs are mechanically the same - a PC is generally representative of its class and species in the greater setting.
--- short-term balance between characters is a fool's errand, long-term balance is a worthy goal.
--- players have to know up front that bad things (including but by no means limited to character death) can and will happen to every character at some point, and the game has to be able to follow through on that threat.
--- the game needs to provide means to overcome or reverse those bad things, at some sort of major in-character cost or long-term penalty.

Well, that's a longer list than I expected. :)
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Flexible character design that allows players to play what they want.

Simple, flexible game mechanics. That is, a simple mechanic that can be applied in multiple situations. e.g. D20 games. Want to hit someone? Roll d20, add modifier, compare to target number. Ditto for saving throws. Ditto for skill checks.

Game mechanics speak to the themes of the game. If you can make the mechanics simple too (see above) that's grand.

Make whatever the main part of the game is interesting. e.g. DnD 5e combat - not interesting. Although I've not played it, I get the impression that gathering clues in Gumshoe is interesting.

As few charts as possible. Looking stuff up during play is a PITA, it slows things down and is dull.

Good art and good layout in your rule books. (This is an aspect of game design, just not game mechanics design.)


Uses a colorful spinner, and involves at least a minimal threat of pulling a muscle during play.
Eh, one on my original systems had a spinner as « dice resolution ». It was for a Labyrinth (as in the movie) one-shot rpg. If there was a doubt that a PC’s action could fail, you’d spin the wheel. Get the primary in your stat and you’d fail. Get a secondary and you succeed with setback. Add a primary for extra levels of difficulty. Wasn’t much of a system but hey, it served its one-night use.


Heretic of The Seventh Circle
My youngest son and I have written some home RPG rules that we are using in our current campaign. The organization is a train wreck, much of the game is derivative, and in short it's a glorious mess. But, we are having a lot of fun.

We came up with some design principles for our game:

1. Character creation should be simple.
2. The experience system should create lots of hard and interesting choices for characters. It should be far more complicated than character creation.
The idea behind the first 2 goals was to create something that is simple to learn, but increases with complexity as you play it - much like chess or bridge.
3. The magic system should not be predictable and have an element of danger for the user.
4. Heavily skill-based game.
5. Use percentiles, (I know this is a dealbreaker for lots of folks), so that players can quickly ascertain their chance of accomplishing something.

I am not asking for you opinion on our design goals - although you are certainly welcome to do so.

I am more interested in what your design principles for a TTRPG would be?
I like the sound of that.

My design goals for Crossroads have changed over the 11 years I’ve been writing and playing and rewriting it. For the current version, I essentially started from scratch so that I didn’t have to worry about artifacts of previous versions. The goals are:

1. The actual gameplay must be simple moment to moment, unless the player has chosen to opt in to greater complexity with their actions. The game should move on a mechanic that can be shown on the character sheet, and everything should reference that mechanic whenever possible
1a. When you need to do soemthing, you can just describe what you want to do, see what skills and specialties you’re good at, and make the check. The meat of the system is in the resolution system, not individual skill rules.

2. Combat, Enviromental, Esoteric, and Social, challenges should not feel like playing different games, but should be designed to most effectively give the desired play experience of that type of challenge

3. The book shouldn’t need to be opened during play

4. Character creation should result in a full character with tools for the various types of challenges, ties to the world, reasons to care about what’s happening, and a character sheet that tells them the vast majority of what they need to run the character.

5. Stuff like magic, tech, investigation, should have both simple skill/trait solutions like throwing fire, jury rigging a car or improvising a grenade, or checking a room for hidden drawers, and more complex long-form solutions, such as complex ritual magic, detailed tech crafting, and investigative sequences.

6. Success should often involve calling upon allies and contacts, calling in favors, making deals that leave you owing a favor, etc, but also just as often just be solved by the abilities of the PCs.


7. The world should feel like our world but with many things just one degree to the left of what we know, and like there are secret worlds around every corner. It should feel weird.

8. Advancement comes from success in cases, not from killing stuff.

9. Downtime should be a core part of the game, including maintaining your normal life, training, researching, recovering from stuff, etc

10. Challentes (combat, social challenges, etc) should flow, and be elegant while allowing the depth to have characters have moves and countermoves ways to try harder, ways to interrupt, etc

11. Players should have authorship of a lot of the game, in conversation with the GM and eachother
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I happened to catch this right before bed, but I wanted to post something before the thread got moving too quickly. These are (roughly) principles I have for designing my homebrew system. If I missed something, that wasn’t intentional. I preemptively blame its being late. The list is numbered, but only the first few are really more important than the others. After that, the order is more what I happened to write when posting.
  1. The target audience is me. I’m designing a game to suit my needs first. If there were a game that did what I needed already, I wouldn’t be doing this. If the resulting system is not to your taste, it’s not for you anyway.
  2. Iterate. Theorycrafting is inadequate to know how well something will work. I’ve had ideas that seemed nice in theory that turned out awful in play.
  3. Create an MVP. The faster you can get something that can be played, the sooner you can start iterating. It doesn’t have to be good. It can be kitbashed out of other games. It needs to be enough to play.
  4. Exploration-driven sandbox. I want to run what I have called the “campaign as science experiment”. We establish what the campaign is about and play to see whether the players can do it.
  5. Post recaps. I try to put session recaps in the 5-words commentary thread with discussions of how mechanics work. I’ve missed a few sessions here and there, but I’ve posted quite a few of them.
  6. It needs to be reasonable. I mean that literally (not figuratively). Players should be able to reason about how things work and make informed decision. Consequently, there should be very little hidden information.
  7. Avoid confusing players. If players are confused by something at first, they’ll probably be confused about it again later at an inopportune time. Keep things simple and avoid special cases.
  8. All tech is on the table. Consider other tabletop RPGs, board games, and video games as sources of ideas for how to solve problems. Don’t do stuff just for the sake of carrying on tradition.
  9. Do not provide mechanics for everything. There should be a core set of mechanics that can be used to adjudicate a variety of situations.
  10. Do not depend on rulings. The mechanics should be complete enough that the GM does not need to improvise a mechanic. Having to do that is okay while designing the game, but it’s a non-goal of the complete system.
  11. Manage conflicts of interest. There is a conflict of interest between adjudicating the game and playing a character. When to allow exercise of discretion (adjudication) should be handled systemically.
  12. Use system to manage the sense of a living world. Factions, events, etc should be delegated to the system as part of implementing #11.
  13. Use abstractions but keep things feeling real-ish. The system is designed for a specific setting. There are not pages of polearms. Technology is fantasy-ish, but it did not happen in a vacuum.
  14. Design for limited prep. I’m lazy. I want to run a sandbox hexcrawl without prepping one. The system should facilitate this in a fair way. #11 and #12 are important to this point.
  15. The milieu is D&D-ish, but the game is not D&D. I have a fantasy setting, classes, magic, etc. Characters have attributes and skills. There is a specific flavor I want, but I’m not aiming for D&D per se.
  16. Aim for compatibility with B/X content. Compatibility is defined as being able to use site-based adventures and translating monster math to my homebrew system. Story- and plot-based adventures should not work.
  17. Play is player-driven. No plots. Do not prep them. The system can (and currently does) fight trying to impose a plot since the GM lacks discretion that could be used to push play in a specific direction.
  18. Use archetypes but keep mechanical heft minimal. Multiple classes can fit on a page. Most of your customization comes from your choice of specialities.
  19. Handle time and distance concretely. The chunk size varies (10-second rounds, 10-minute turns, weekly downtime, daily overland movement), but it should remain consistent. That helps with #6 and #13.
  20. Resource management should matter. If the game is about exploration, there needs to be an element of skilled play in how you go about it. There are systems for handling attrition and supplies.
  21. Aim for 16 pages A5 for the player-facing rules. This is a goal I have for the amount of rules I want players to have to know. It excludes things you pick like specialities, spells, etc nor procedures, GMing advice, etc.
There are some other aspects that are important, but they’re more a consequence of the design rather than a principle. For example, all magic uses MP. If it uses MP, it’s magical. This keeps it very simple to know whether an effect requires Resilience or Magic Resistance to resist. Does it use MP? Then magic. Otherwise, no. Everything has the same calculation for HP (4 × level + 5 × Endurance) and MP (3 × level), but I don’t consider that a principle either. Same for armor and mitigation, which has had several revisions with very different designs.
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