This was pretty good. I like the use of multiple characters and gameplay styles for each of the characters. It helps varies the gameplay and makes it more interesting. I did find the Ryu segment the least interesting of all the campaigns, as it is pretty short and unwinnable, not to mention it seems like it was added in order to give context for the beginning of Street Fighter x Sonic.
Also, the segment in the secret campaign gets pretty glitchy during the sequence where Knuckles has to jump on a ton of platforms. Sometimes Knuckles will fall through the platforms and fall into the pit. Also, the scene here War Machine doesn't really have any context and kind of comes out of nowhere. I mean, one minute where jumping on top of a bunch of platforms, and then suddenly where in the middle of a conversation between Knuckles and War Machine.
Still, this was a pretty good fan game, and I think as time goes on, future games you make will get better. Keep up the good work.