At last, we were able to find an archive for XQuest! This game is a flawless conversion of the arcade shooter Crystal Quest, which was available for the Apple Macintosh and Apple IIGS, among other ports. Dozens of different aliens, a record function for replays, and two-player co-op support await you!
The premise of the game is that an invasion fleet of hideous Mucoids is hurtling towards Earth -- intent on blasting it into tiny steaming shreds of radioactive grit -- and only your ship, armed with the latest weaponry, can hold them off.
The gameplay involves moving your little spaceship around an arena, which has three entrances through which enemies come pouring in. There are mines, crystals, bonus powerups, extra lives and all kinds of enemy alien vessels. For example, there are Grungers, which will block your path; nigh-invulnerable Meebs, which detonate if you fire upon them too often; Retaliators, who launch homing missiles at you if you kill them; and even the very friendly Tribbler, who seeks your close company at all times (which isn't good for your health when there are too many of them).
Fortunately, you are equipped with a main weapon (primary mouse button) and a limited number of smart-bombs (secondary button) to help you on your mission. If you manage to collect all the blue crystals, you can escape through a small exit at the top and start again in a new, more difficult level, with even more ferocious enemies.
In short, this is a very addictive game: On the first try you may not like it, but after a while you'll find yourself unable to stop playing it.
If you happen to have played, or would like to play, the beta version of this game (with a circle instead of a spaceship, and a much smaller exit), it can be found in the folder "xquest 1" included in this archive.