This list is for people who are making 3D games and/or are comfortable using more complicated software than what is presented in the other game creation software list. Some of the tools below require knowledge of how to code.
The Game Programming Wiki can be a huge help.
This list is incomplete.
- GarageGames has created the Torque3D engine which is open sourced.
- Unity3D is a popular option and if you’re starting out in it you may want to check out this free Unity training or Unity’s own tutorials. Great for indie startups
- UDK (Unreal Development Kit) is another popular choice which is also great for indie startups.
- cryENGINE is for really really nice looking games, this engine is used for a lot of military simulators.
- Source is Valve’s in-house engine that can be used to make your own games.
- M.U.G.E.N is the tool of choice of fighting games.
- Gameplay is an open source cross platform 3D game engine for indies.
For a complete and incredibly long list of game engines take a look at Wikipedia’s category page.
If you’re building something designed for Android, this collection of Android-specific documentation may help you.