So far I have completed Beta Level 1, and I have to say; this is looking pretty amazing so far! I've noticed a few problems though: there seems to be some slight lag, and you can only collect coins if you're right-side up. Aside from those problems, though, I love the engine of this game. The graphics are superb, the music is great, and the morph powers are extremely innovative. Even in its beta stage, the game is turning out to be superior to Super Mario 63 in every way. Well done, Runouw!
I'm about to go play Beta Level 2 now, and then I'll try out this seemingly incredible (at least, that's the impression I got based on what users in the chat had to say) level designer.