Hopp
Hopp is a free lightweight game framework/engine built in c++ using SDL and OpenGL.
It allows you to make 2D games and some simple 3D games, focusing on graphics & input.
Hopp is a one-man project,after announcing the first beta a long time ago, i realized
that it was poorly designed and that it would be very difficult to add more features later.
So i spent almost a year rewriting it, and i´m close to releasing it again.
How does it compare to existing game/graphics engines? Well, Hopp is not as raw as OpenGL but not as big as Ogre(). I think it is more or less comparable to HGE or Löve, for example.
Hopp is very simple to use, and has quite some features:
-2D & 3D graphics.
-It allows you to organize your apps using "states".
-Scene graph, supporting object parenting.
-Material system with pixel & vertex shader support (GLSL)
-Every node in the scenegraph can be a camera.
-100% customizable render pipeline.
-Resource management.
-Provides basic integration with ODE.
My plans for it are finishing the python bindings and adding more format loaders.