Like earlier games from Id Software, such as Wolfenstein 3D, Doom takes PC games to new heights. If it were just a mindless shoot-'em-up exercise with good graphics, no one would care, but it combines all that with a design that requires you to run a complicated blind maze and challenges you to winkle out the game's secrets.
Games players, like readers of mystery novels, hate reviewers who give away the plot, but look out for hidden switches at all levels of the game. You have to find those switches and activate them, although some don't look like switches at all. You might have to jump off a platform and land on a lighted ledge in order to open a door in another room; some do and activate a door audibly - but then you have to find the door. Some doors are locked until you find the right keys elsewhere on the floor. And so on. Getting through a level to the coveted 100% secrets rating is difficult. My stock will plummet in some quarters, but I confess that I can't do it without cheating (the cheat codes are distributed across the Internet).
Version 1.0 of Doom arrived last December, followed by several upgrades - 1.2, 1.4 and 1.666. The version you buy by mail order has three levels; the shareware version that can be downloaded from almost any on-line service is just the first of those.
Doom II is a commercial release with completely new levels and even a couple of new weapons and monsters. What's impressive is how well the program's authors have managed to sustain the quality of the game: there's no repetition and the levels get harder and more inventive.
Besides the ordinary single-player mode, Doom can be played co-operatively or competitively (Deathmatch mode) across a network, over a modem-to-modem link, or even over the Internet. A warning to the sensitive: Doom is pretty gruesome, particularly at the more difficult settings. But then the same can be said of Grimm's Fairy Tales.