I am not sure, but I think it is a Mac game from late 90's - Prime Target, or something similar
You are most certainly right, Amok! And to answer your question, FraterPerdurabo, it actually runs on the Marathon 2 (M2) Engine, which Bungie Studios made for the two latter installments of their Marathon trilogy. It's also used by such games as ZPC, which I'm sure most of you know of, and Damage Incorporated (Or Damage Inc.). Both of which are FPS games from the mid to late nineties.