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Designing Mechanics and Systems for 5E D&D

A topic by Zargo Games created Mar 17, 2019 Views: 414 Replies: 3
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note: this is adapted from a mostly defunct blog I run so idk how it will look on a forum post

One of the things I like most about 5th Edition D&D is its simplicity. While it is still significantly more complex than systems like Powered by the Apocalypse or FATE, it took many of the complex ideas from past editions of the game and streamlined them. 5th Edition isn’t perfect, but it is my preferred system for most campaigns. Still, there are things that 5th Edition just doesn’t do with its core rules, so improvisation and rulemaking are important for anyone wanting to run more advanced games of D&D. Making supplementary rules for your games can be very rewarding, but it can also ruin your games if you don’t know what you are doing. Here are some tips for creating your own mechanics and systems for 5th Edition D&D.

Keep it Simple. 5th Edition is a relatively simple system, so unless you have no other option, keep your homebrew rules simple as well. This will help make the rules easy to explain and easy to follow. While it may be tempting to make your mechanics granular and have modifiers for every little thing that could affect it, you should stick to only having modifiers for significant factors and have the minor effects roleplay-only.

Keep it Consistent. This goes hand-in-hand with keeping it simple. If your rules work the same way every time, then it will be easy for your players to remember and it won’t cause unnecessary confusion during your game. If you decide to change the way your mechanic works (perhaps you playtested it and realize something doesn’t work the way you intended it to), make sure to let your players know so that they won’t be confused or feel cheated by a sudden change in the rules.

Look at Other Games. I know a lot of people reading this exclusively play D&D, and perhaps even only 5E. That’s fine, not everyone enjoys every kind of game, and while I’d recommend branching out and trying new games, do what’s best for you and your group. However, even if you don’t intend on playing other games, it is helpful to look at other systems that do what you’re trying to do. Other games often have mechanics for whatever you’re wanting to do, and those mechanics could serve as a baseline for your homebrew, even if they have to be altered dramatically to fit 5E.

Remember what is Practical. It can be tempting to lift rules from video games. However, keep in mind that video games often use significantly more numbers than tabletop games because the consoles can calculate the results of the numbers instantly while you would be stuck calculating the numbers yourself if you use a similar system. This can drag games down if you have to deal with too many numbers, so if you do take an idea from a video game, make sure that the math is easy to handle. Concepts are easier to adapt from video games than direct mechanics.

Conclusion. Making a system to fit your campaign can be challenging, and there’s no specific formula for crafting the perfect homebrew rules. Learn to be patient and always think things through before you implement them, and remember to always keep your rules simple, consistent, and practical. If you follow these guidelines, I can’t guarantee that the mechanics you make will always work or be great, but they will help you in the creation process and lead to less headache and more success.

What other advice do you have for creating mechanics and systems in 5E?


Here's some more advice, that I've gleaned from running a game with a lot of homebrew rules:

Don't be afraid to add rules temporarily 

Not all rules have to alter the entirety of 5e, some can be included just for a session or two. I adapted rules for B/X D&D used to simulate Mongolian wrestling bouts once. The original rules suggested using them as an alternative to combat, I used my 5e version for 1 session for a wrestling tournament. It went really well and provided a nice break from the normal flow of play. 

Write rules players can bend

A lot has been said about when a rule should be written and when you should rely on making rulings. When you write a detailed set of rules, it can take away some of the freedom to act in unpredictable and exciting ways. The combat rules 5e uses are a pretty good example of this, it feels like a player can only act within a set of predecided actions. So when you write rules make sure there's room, whether it is stated or implied, for players to bend them in ways which may require you to rely on rulings. 


these are both very good points!


Add Variety not needless Complexity

You can usually get interesting result by hijacking existing material and concepts. You don't need to totally reinvent the wheel, often you can just grind the serial numbers off something else, put new paint on it, and drop it into the game as a new rule.  But don't make new rules just because you think another 7 moving parts is going to make it 'good'; sure lots of people love their crunch, but if you can get the same variety without making it a Rube-Goldberg of die rolls and tables and whatever else... then you've achieved your objective.