Reality Factory is a program that - in conjunction with other tools - allows you to create 1st and 3rd person perspective games without programming! Reality Factory is built on top of the powerful Genesis3D Open Source engine and supports all major 3D graphics cards.
Reality Factory provides most of the tools you need to make a game. You will still need a program to create actors (characters and props in your game) and software to make textures with, but what you won't need is a C/C++ compiler and a couple of coders to build your engine for you. By using objects called "entities" which you place in your world, you can set up a game - with audio effects, multiple soundtracks, and special effects.
Reality Factory is intended to be a "rapid game prototyping tool" - it is able to make playable, interesting games across a wide range of genres but it's not optimized for any ONE kind of game. While you can certainly make a good game with Reality Factory, and even give it away and/or sell it to others, you won't see the kind of blazing optimized speed that you would in other single-purpose engines (like Quake 3 or Unreal Tournament).