Is it possible to add a mutation temporarily? For instance, taking a bath giving the player weak scent for a set amount of time?
Through the code? Yes, as much so as anything else. It’s definitely not a JSON-only thing, however.
Though if I was going to do that I’d probably rather do it through the effects system than the mutations one. Have taking a bath give you the “clean” effect, then have a line in the scent code that made it so that the scent levels you gave off were lower if you had the “clean” effect. Neat, tidy, and with minimum work, and it would even keep it’s own timer so you didn’t need to worry about removing it after a certain amount of time had passed.
Sounds great. You schould also get a moral boost if you stop smelling.