I like where you're going with this. Having the ball change temperature to get past certain gates/doors is a good way to dangle the exit in the player's face but have them go around the level figuring out how to end up in front of that exit with the right temperature. Lot of potential for a puzzle game with this! The ball controls felt good too.
Like you mentioned in an earlier post this is just a demo. There's a lot you can do with this and I'd say keep working on it if it still interests you after the jam.