There's a totally free version of Unity. I think if you download it and try it out for awhile, you'll discover that it would be extremely easy to build any kin

There's a totally free version of Unity. I think if you download it and try it out for awhile, you'll discover that it would be extremely easy to build any kind of unique game mechanic you might want in it. Probably easier in unity than anything else simply because unity will still take care of a lot of stuff for you. I wouldn't say Unity forces you into any assumptions about your game. (for instance, many people think of it as a 3D engine, but famous 2D games were built on it, and the developers gave it the capability to do 2D right.)