What an excellent, innovative concept! I could really see this being taken much further with even more common platforming concepts (enemies - "you can no longer stomp on enemies", groundpounding etc.). Really, really great, thanks!
The "press R at a checkpoint to reset the entire level" needs to be changed to something else. It's driving me insane when I accidentally reset The Final Challenge, for example.
The reindeer is really cute and the snowy village background looks very nice. Generally, the idea is worth developing further - adding some sort of shop and powerups, maybe... you've got a nice, solid base to build off from, at least! :)
E, F and X seem pretty awful as shooting keys for me (I play with WASD), mostly because they are TOO close to WASD. Is there a key on the other side of the keyboard (J, K, L?) for shooting, and if not, could you add one of them for it?
Thank you for raising this bug. Fixed!