Good concept executed pretty well. The controls didn't trouble me much, but I do think there is room to improve them. Perhaps make Z and X toggle whether each player is frozen, rather than need to be held? Similarly, instead of the spacebar perhaps just automatically move to the unfrozen character if one character is frozen, and move to the character further in the direction the player is trying to move if both characters are unfrozen.
All in all, enjoyed a lot. Would happily play again if you ever modify the controls or add new levels.