Unreal Development Kit http://www.udk.com/download

Unreal Game Development

XNA Game Studio Express (DirectX and C#)

Download: http://msdn2.microsoft.com/en-us/xna/default.aspx

Forums: http://forums.xna.com/ Starter kits: http://creators.xna.com/Education/StarterKits.aspx#ShipGame

 

OpenGL C/C++

Tutorials: http://nehe.gamedev.net/

Forum: http://www.gamedev.net/community/forums/forum.asp?forum_id=27&forum_title=NeHe+Productions

OpenGL.org Forum: http://www.opengl.org/discussion_boards/ubbthreads.php?ubb=cfrm

FAQs: http://www.opengl.org/resources/faq/

 

DirectX C++

Download: http://www.microsoft.com/downloads/details.aspx?familyid=86cf7fa2-e953-475c-abde-f016e4f7b61a&displaylang=en

Tutorials: http://www.riaz.de/tutorials/d3d.html

Forum: http://www.gamedev.net/community/forums/forum.asp?forum_id=10

Forum: http://forums.xna.com/

 

Any bare bones 2D API

Example: Gtk: http://www.gtk.org/

 

Java3D

Download: https://java3d.dev.java.net/

 

MASON Multiagent Simulator (in Java) Download

Unity Engine Download

Game Engine Databases - Include Linux sections

http://www.devmaster.net/engines/

http://cg.cs.tu-berlin.de/~ki/engines.html

 

Irrlicht Free Open Source 3D Engine

http://irrlicht.sourceforge.net/

 

DarkGDK (high-level game-specific engine)

http://gdk.thegamecreators.com/