This is big, so maybe it’s not what you mean, but, BitD has the best downtime cycle of any RPG I’ve seen so far. Ars Magica may be the only other game I know of that has a similar downtime character cycle. For a long time, this has been a big issue for me, because while other games have downtime rules, they’re tacked on, and boring to both players and the DM. D&D is a perfect example of that. Most people don’t use D&D’s downtime rules, and for good reason: they’re not fun.
There’s something about downtime that’s a bit intrinsically tedious. It’s always a bunch of bookkeeping. The problem with ignoring it is that you have these weirdly short character arcs, in which PCs go from being nobody to being heros in an oddly short timespan. Weren’t you that random guy in tavern I saw two weeks ago? No you’re the savior of the realm? What? And that’s the other problem with ignoring downtime: PCs become murderhobos, because that’s the good part of the game! Figuring out where all the characters live, sleep, eat, and so on is dumb and boring.
So, BitD does two very smart things. First, it moves some of the excitement to the payoff and downtime cycle. Shopping, entanglements, incarceration, all happen during downtime. Second, it gives characters mechanical advantages that come into play during downtime. You’re good at these downtime actions, so you’re more inclined to do them. Those two things make the bookkeeping part of the game much less bad.
Not only does downtime bring in a bunch of realism to the game, but also a lot of potential complications. Murderhobos don’t have lovers, mothers, kids, hobbies, jobs, and so on. Characters that have downtime lives, might. That’s a huge advantage. Also, as I mentioned, it makes the change player characters go through a bit more believable by stretching it out over a longer in-game time period.
So, yeah. a real, good, downtime cycle should be ported to other RPGs.