Simple Open Source 3D Game Engines?

Zenitram asks: "I'm trying to find a good open source/free, 3D first/third-person game engines. I can write basic scripts and make basic programs in various programming languages, but when it comes to making 3D worlds I do not have the skill set. Most of the Open Source programs I've found are not for beginners. I've found some pretty good commercial programs, however the game I am making has no chance of ever making a profit. As such I don't really want to invest money on a personal project. Any advice?"