If I were you I would read up on some of these articles to understand the makings of a game. With that you can make an informed decision on what direction you'll head in.
GameDev ReferenceFrom there take a look at the forums and workshops there, but read through it before posting. Find what part of the development you'll be involved in, whether it's programming, modeling, texture artist, game design, etc. Build up your skills and then make your idea known. If you come along saying you got ideas, some will not take the project seriously, because people have plenty of ideas but don't execute. If you present your idea with WIP shots or anything to show someone it will make it easier for others to get behind your project.
As timu sumisu mentioned Blender is an excellent engine/content creation
BlenderOgre3d is an excellent graphics engine
Ogre3DHere is a more in depth list of free game libraries
Game LibsI'm not trying to say you must be an expert to pursue this endeavor. Some of these projects are great fun if you start with a small group of folks that want to learn along the way with you. Best of luck.