I love games where you combine stuff.
I feel kinda conflicted about the combat, I dont think it really fits into this game. The puzzles were enjoyable, making fire to melt the ice or making ice to cross the water. Level 3 I sorta just skipped or it was very easy.
If you wanna expand this game your focus probably should be on the combining part and desigining puzzles around that because that's where your game shines.