I'm looking to make my first 2D sidescroller for android, and would prefer an open source engine good for 2d games. I might eventually have 3d backgrounds too, so if it can handle those that would be ideal. I know flixel has a few c# ports, but whatever read about it suggests it has some performance issues in the transition.
So, if anyone has any suggestions on where to look / features ideal for the android / or even engine suggestions please let me know. I don't really have the practical experience to evaluate the quality of an engine yet.
Which free engines stand out besides flixel? Unity is too expensive and the point of the project is for learning the development process / best practices. If it brings cash in eventually that's just a bonus.
Added: I had completely forgotten about using Monogame. So, any other good engines or ports of good ones to C# besides Monogame and Flixel?
