Thanks for the feedback! Hero/dark/chaos/character Chao would require an entirely different sprite set for all of them, yeah. I tried to include many other ways to customize your Chao to make up for it though.
Balancing the halfpipe minigame was rough, because I personally had the same issue as you that it was too easy, but many people I had test found it too hard. I would rather have it be easy so anyone can enjoy it and people who are good at it can keep going than have it be hard so that not everyone can enjoy it. Keep trying to get further, if you play long enough you may find something special :)
I will look into adding a finish line to the races, that is something I could do pretty easily and I'm not sure why I didn't before.