I'm always a bit weirded out by these super good fangames that clearly are a sprite swap away from being viable commercial products because... man, just make your own game, you clearly can do it. But at the same time, it would likely not be nearly as popular without it being skinned as a Sonic or a Castlevania or whatever, which is a bit of a bummer.
In other news, go play Penny's Big Breakaway. It's good.