This engine is the code behind "The game Creator's" FPS Creator development tool, A powerful, yet rough FPS engine.
This is a very good engine for beginners and advanced users alike. I have been making games with this for a while, and it is one of the few "good" game creation softwares that i have stumbled upon. Also, anyone familiar with the Slenderman's Shadow series should know that this engine was used to create those maps, so you know that it's pretty damn powerful!
If you're looking to start a career in game development, then the FPS Creator isn't a bad choise. The map editor is pretty basic, add some grass there, place a few guns and enemies here, it's all done with a few clicks.
You can make your own single player campaigns and multiplayer arena games. Some people have even made their own games and sold them online and in shops. For example, you can look for Robert D. Anderson & The Legacy Of Cthulhu on websites such as amazon, eBay, etc and the developers don't have the pay The Game Creators a single penny.
What really let's the FPS Creator down is its dated and buggy engine. The graphics look dull, the AI is bad (even though you can edit the AI scripts), your levels can glitch up when you have a lot of entities on the map, etc.
As for content, you have different enemy types, weapons, objects and scenery based on which time period you're making your game in (World War II, Modern and future). You download more stuff for the FPS Creator from the Game Creator Store either for free, or pay with store points.
Overall, the FPS Creator isn't bad, but it does have its problems and the asking price on The Game Creators website of £33 is kind of a rip off. Between £20 - £25 would do.
As for the experts who know how to make maps with other game engines (Source, Id Tech, Unreal Engine 2, etc), this is not the package you're looking for.