*www.yoyogames.com/studio is pretty good, not open source though
something more advanced then try
Unity - Download and Start Creating Games can pay for pro features
and
Free Game Engine for Indie Game Development | UDK Unreal Developer free for non-commercial use
any particular game you wanna make? there are specific open source engines available for particular kinds of games
for example, canabalt is good for making a 2d side-scrolling endless runner *github.com/ericjohnson/canabalt-ios