I don't like my idea about incentivizing using less pieces anymore after your explanation! It does sound way better to not overload the player with additional goals they would feel obligated to optimize for.
Choosing the next area thematically does sound like a good progression system, as well as limiting piece types in an area.
I also agree that Shortcut is strategically interesting, it just makes me sad that you essentially spend money to get less gameplay...
Also also went back and played a run as a Pawn, was way more hard and interesting, loved it! Had to make a lot of sacrifices, didn't have a ton of pieces and seeing the Reincarnation passive was awesome, hope there will be more synergies like that. Vampire just seems busted now compared to others, both as a class and a piece, it straight up solos multiple hard levels, would pick it over a queen any day and it's only $4 somehow :D
Now that I knew what differently colored pieces meant I liked them a lot, actually!
Also also also wish there was a free single-move undo like in ItB, was sad to lose money a few times due to a misclick.