Sonic Physics or something

Do you think you could explain how running up loops without falling off works?

How do you make your sonic playable characters well playable?

How can I add a model onto this? (Yes, I know. Im not the best with logic. Its prob. also very easy but I dont know)

I like it but how do you make the bean a sonic when i tried the bean falls over, sonic keeps falling over or sonic just does nothing and floats

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