[Coriolis]

The "Q3TA engine" is just 1.27 version of Q3, as near as I can tell. They use the same executable, after all.

An "engine" is basically a set of tools for making a game more quickly. A "graphics engine" is an already optimized way to store and render your 3D assets. A "sound engine" is the same for sound. A "game engine" typically includes a sound engine, a graphics engine, input control, development tools, etc. It almost always has a networking engine built into it as well, though one might imagine a single-player game engine.

The quake3 engine had a couple big advantages for us; performance and familiarity. Our coding staff and level designers were familiar with quake technology. When we started development, no other licensable engine could boast the rendering speed or quality of quake3.

We could have achieved the same results with another engine, or even starting from scratch, but it most definitely would've taken more time.