MAX+ is a more refined, and updated version of MAX+. Sonic MAX is a very accurate engine, but needs a lot of work.
It's relatively easy to learn, but can get challenging quickly. This is one of the trickier engines to use, as Unity uses a common scripting language called C#. It's creator Shiro also did some shady things, but that's an entirely different post. This engine is not as accurate as some of the other engines in this list, but it's worth mentioning. GMate is a 2D Sonic engine for Gamemaker 8. It really depends on if you want your game to be 2D or 3D.
