Irrlicht Engine

Just in case you have heard of this game engine, and want to take a peek to its source code... I started using it some years ago, and has some nice features
like audio playing, network code, client/server, convex collision detection and a custom script language, the torque script, and much more stuff. It is based partly on the first half life code, and the second quake, though several years later, it started supporting custom shaders, and many other interesting features, i don't know if this would be present or not.

https://github.com/GarageGames/Torque3D

It is released under the MIT license.

Have any games been written with it? It just looks like a FPS game template.

Hmm, I see: Penny Arcade Adventures, Fallen Empire: Legions, Buccaneer, Dreamlords, Marble Blast Ultra. This with (I guess) the professional version. Are these games any good?

Torque was used on Tribes and Tribes2 originally. the original engine is fairly old, but got updated many times. Though that is not a real sample of the quality that it can achieve.

Like any other engine, it has been used by many people, but not much were actually successful with it. FPS's is one way of using Torque, it can be used any way really.

This is their original web, http://www.garagegames.com