I loved the idea of having two characters with different abilities! Being able to use them both to solve puzzles was great, especially when finally figuring out the solution. It's a minor thing, but the unique abilities made sense too - heat does freeze things, and hot things jumping twice just... makes sense! The levels did feel sort of long at times though, just moving one character to point B, then moving the other one - but it was nothing too bad. Some more obstacles to avoid would've been a nice addition too.
The graphics were nice, and it was clear which character was hot and which was cold, so good job on making it readable! I especially liked the cutscenes, and they added some nice context to what was going on in the game - it's always nice to have a bit of story. Some more visual flavour would've been nice, like a bit of background décor, or some shrubbery here and there, but it's still fine without it. Sound effects and music would've been a really good addition, though, since the game felt kind of empty without them.
I enjoyed this nice puzzle-platformer kind of game, and I think it has a great idea behind it - great work on making this game!