An urgent job sends you to GenCorp, where a man called Derrida urgently needs a parcel. But something has happened and the place is filled with bio-weapons and security systems through which you will have to find your way.
To reach the man, who is in the 89 level, you will have to cross nine levels filled with puzzles, hidden buttons, secret rooms, electric eyes and a few keys to reach each of the elevators that will carry you to the next one, helped by a few objects found in your way, mainly grenades, a shield or a time stopper with luck and perhaps a bomb. But your main tool and weapon will be the laser gun.
This gun shots bounce around and the correct use of them will be necessary in many puzzles, where you will have to find how to shoot. And also with a bit of skill will be really helpful against your enemies.
Those enemies are mainly the neogens, artificial beings with mimetic skills that come in four variations. The more common, the generation A is a red ball that jumps over its preys to devour them, as this takes a time a laser shot coming back, and luck, will free you; the second, the generation B are blue pillars of which if you do not take care of will quickly jump over you; the generation C are well hidden and dangerous; and the generation D awaits you somewhere in the building.
Apart from this there are other dangers in your way. Grenade launching towers, electric tiles, laser and mines had been activated as security measures. But they do not recognize allies or enemies, many have been trapped and you are the only one who can rescue them, in exchange of some information and help, and also a live per rescued person.