unreal engine - free?

hello,

i’m a newbie and so I wonder if anyone knows of an engine that has the same capability as unreal engine. Is there a free one?

Which version ? For what needs ?

You have Quake 3 fully open sourced, I like the ioquake3 fork wich is easily compilable with current compilers :
http://ioquake3.org/

A bunch of infos and links to other free engines :
http://en.wikipedia.org/wiki/Id_Tech_3