In order for a game to be considered balanced, there needs to be a reasonable chance for every alignment to achieve its win conditions. People believe that whether one team wins or loses should be based more around the players on the team than structure of the setup, and thus the setup should be made such that each team's victory depends on how the players play their roles. As such, if a setup does not reasonably allow a team to win, then it can be considered unbalanced.
Note that balance is an objective trait to a setup, and is not tied to how the game actually played out; a setup can be unbalanced but still result in the weakened team winning the game.
Common Balancing Strategies
- One of the most common ways to balance a game is to do a "worst-case scenario" analysis; if the town used their power roles perfectly, how long would the game last? How about if the scum play perfectly? A game ending day 2 or 3 might be unbalanced.
- Also ask yourself, if everyone were to fullclaim their roles day 1, would the town be able to, solely through everyone's night actions alone, win the game? If so, then you have too many power roles. Toss in some vanillas, or even a miller.
- Ask yourself what players are going to expect, and take that into consideration when designing the setup. Putting in a backup cop will make the town think there is a regular cop, even if there isn't, which puts the town in a worse position than if you just had copless town without the misleading backup.
- As a general rule of thumb, giving the town as many vanillas as there are scum roles is a good way to keep your setup balanced, since it'll restrict how much you can give the town (and thus how much you feel comfortable giving the scum). Putting in a ridiculous role is perfectly acceptable so long as the rest of the setup is balanced around it.
- Ask yourself, what are you trying to accomplish with the game? If you want everyone to have a fun time, then when designing the setup, ask yourself, "if I knew nothing about the setup, and I joined the game with this role, would it be fun for me?"
Uncommon Balancing Strategies
- Some moderators make their games "self-balancing," by activating certain power roles if members of a team die too early. This stems from the idea that a team becomes substantially weaker if it loses a power role too early, giving the other team a huge advantage for the rest of the game, especially since actions are so chaotic and random in the early stages of a game. For instance, a moderator might design the setup so that if the town cop is lynched Day 1, a preselected town vanilla becomes a tracker night 1.
- Other moderators engage in a post-RNG balancing act, altering roles or the player list to better even out the teams. For instance, even if the setup on its face is balanced, putting a bunch of "strong" players into town power roles, and making "weak" players all scum, can arguably be just as unbalancing. The drawback with this approach is it violates the assumption of randomness which most players hold sacrosanct, and if too widespread, risks players gaming the setup with arguments like "the mod wouldn't have made Strong Players A and B both scum!"
If a game is so wildly unbalanced that there is practically no way for a particular alignment to achieve its win condition, then the setup is considered broken. Generally you can tell a setup is broken through the balancing strategies above, but a broken setup is always obvious as the game is being run.
Players, being wily, often seek to engage in breaking strategies, or ways to make the setup broken so they can easily win. Many of the more egregious breaking strategies are outlawed by the standard mafia rules.
Generally players dislike playing in a game they feel like they "couldn't win." Whether the setup was actually unbalanced or not is a different story.
Still, it's generally a good idea to have a second set of eyes look over a setup before you mod a game.