Wow, this is awesome! Shoutouts to Cammy, the Vault theme is gonna be in my head for a while. I love the retro aesthetic of it all, very convincing, really feels like a forgotten game from the late 90s, like an alternate universe DK64.
The marbles themselves feel really satisfying and tactile. The sound design and the subtly different physics for them are great. I love the wooden one especially, it feels super satisfying to just barrel it around.
The main thing I think could be improved is the overall structure of the world. There’s quite a few ways to softlock yourself (luckily none I found that couldn’t be fixed with a reload; the funniest one was dropping into a frozen part of cistern as Glass, causing a permanent loop of deaths), I found a ton of difficult to reach unlocks that didn’t seem to do anything (especially in the Cistern, lots of bars opening, checkpoints appearing, that I didn’t need at all to progress) that just obfuscated the real progress, which was at times hard to find. Finding out where to go for the 5th marble was a bit of a frustration point, but from there on out it was smooth sailing to the end.
Still, this was a super satisfying entry that I enjoyed a lot. Impressive amount of content for a jam game too! Really great work.