so how im gonna make a good full 2d sonic game with a engine like sonic worlds but i dont have to pay to make and use it?
I'm not entirely sure what you want to do with it, but there are probably several projects that would allow you to do that. There might be a 2d project for Unity or some other engine that has a more capable free version.
Personally, I created an engine called the Motobug Engine primarily due to frustrations like this (
here's a game that I made with it). I even created a
level designer to work alongside it. You can try to use that if you'd like, though I don't really know if it is quite beginner-friendly yet, especially since I haven't finished writing the documentation. It is all based on web technology, so it is completely free to use, and even works on mobile devices! Let me know if you want help getting it set up.
Other than that, there are many frameworks both here on SFGHQ and online. All of them are probably in various stages of completeness, with varying amounts of accuracy to the genesis games (assuming that's what you're aiming for). Many are probably poorly documented, but that sorta just goes along with the territory.