Unreal Engine 4 is free and they are giving out Grants for developers and kickstarters with Unreal Engine. Its almost unbelievable because even Valve and AAA companies aren't doing stuff like this. Think about it... which engine has been used the most for AAA games and Indie Games? Unreal Engine I know a lot of developers are using Unity 3D as well, but there are literally hundreds of games, mods and projects done with Unreal. I would have to say it is the most successful engine ever!
