It would be nice if one-shots and Throne Rooms had types that cards could refer to. I made duration cards and Scheme and Band of Misfits anyway though. I think that's as close as it gets.
I don't get that. You mean a type like "Action/One-shot" or "Action/Throne"? How would that simplify the mechanics of Duration/ Scheme/ BoM? Would these card types open further design space?
Like Action - Event for one-shots and uh something else flavorful for Throne, Golem, etc. As I noted, it didn't stop me from doing the things I wanted it for; maybe it slightly opens up design space, or maybe I could always work around it, and it just means some wordings would be wonkier.
It would have been simpler for Band of Misfits to play the card, rather than changing into the card. This was problematic with one-shots, duration cards, and throne rooms used on duration cards - and durations have a type to refer to (so it could conceivably say non-duration), but one-shots and thrones don't.
Scheme has an issue with the same set of cards. Scheme has this wonky wording that has you choose a card at the start of clean-up and then looks for you discarding that card from play - which tells us that it wasn't a one-shot or duration card that was sticking around or throne on a sticking-around duration card. There were a bunch of wordings of Scheme before I found that one. For example "When you discard this from play, you may put another Action card you have in play on top of your deck." Simpler, doesn't work with those three cases (incidentally doesn't let you Scheme the Scheme and doesn't double with Thrones, both of which went back and forth as I tried different wordings).
There are other issues. Doubling a doubler is often problematic in games (in this case, King's Court a King's Court). You can just not allow it with a type. I don't know if I would have (who doesn't like King's Courting a King's Court) but it wasn't an option. Duration cards require tracking when Throned, so there's a rule that Thrones stay out, which is kind of wonky, and in fact I reversed a ruling on King's Court / King's Court / duration. You could avoid the issue by saying non-duration on Throne, but I couldn't because Throne came first (and you could avoid it with non-throne on thrones). In the Seaside rulebook it refers to something like "actions that play/modify" actions, which confuses people. A type would clear that up.
Again this is all hypothetical; I don't know what the wordings would have been if I'd had more options (i.e. maybe they would be the same as they ended up), and in the end I did the cards I wanted anyway.