I'm glad that you liked the game!! Thanks For Playing!! Ye I'm sad too that the game is very short :C
It originally was like you suggested (inverted up/down controls for the upside down player), but it was really unintuitive and a lot harder to control, so i change it to the way that it is now!!
And about the walking animation... Maybe you're right, but i really like how it turned out the character, so i don't think I'll change it (^u^)
Still, Thanks for the feedback!! Really Appreciated!!(^D^)