Hey man. Nice work on getting your game released. For a first game, it seems you really put in an effort with all the customisation options, leaderboards & statistics. I have to say I'm impressed!
I really like the game too. It's an interesting idea and it's fun to play (I prefer hard mode because it's faster, although I suck at it and die very fast!).
The only criticism I'd give is that every time I go to the main menu, I'm asked to create a Gamer ID. It'd be nice if it only asked you once, since you have the option to sign in manually anyway.
Overall nice work though!