Crystal Quest

There was once a time when Macs were pretty well regarded for their games, and Crystal Quest was their Tetris -- engrossing, addictive, and impossible to beat.

You used the mouse to control a little spaceship that looked like a hockey puck, collecting all the crystals in each screen-sized level. Once you had all the crystals, a gate at the bottom of the screen would open up, permitting you to escape into... a slightly harder version of the level you just played, with more types of enemies, more land mines, and more crystals you have to pick up. This masochistic treadmill of impending doom was memorable enough to its players that they eventually ported it to the Xbox Live arcade, with (optionally) modernized art.

Also of note are its slick graphics (for the time; it was the first color game on the Mac) and the bizarre, often hilarious sounds made from distorted voice recordings and cheesy synthesizers. Most infamously, the level completion fanfare was a recording of a woman making a suggestive gasping sound, something that apparently had to be censored for the Xbox port.

Tropes used in Crystal Quest include:

Blob Monster -- The Dumple.
Breather Level -- In the sequel, every third level is a "bonus wave" with no mines or enemies, just goodies to collect... between a pair of Advancing Walls of Doom.
Bullet Hell -- Zarklephasers "emit bullets like a hail storm".
Collision Damage / Everything Trying to Kill You / One-Hit-Point Wonder -- Touch anything not collectible, and you're dead. Yes, even the sides of the gateway out of the level. Did we mention it's Nintendo Hard?
Cool Gate
Destroyable Items -- Bonus Crystals.
Endless Game
Every Ten Thousand Points -- Extra lives are awarded "at depressingly rarer intervals."
Everything's Better with Cows: Space Cows.
Frickin' Laser Beams -- Fired by Menaces, who are actually "something of a respite after Zarklephasers."
Gotta Catch Them All -- Each level's crystals.
Harder Than Hard -- Hold down Option to play Super-Fast Mode, if you dare. High scores achieved in this mode will be marked with an asterisk.
Heavy Metal Umlaut / Stealth Pun -- Crystal Crazy's tranq-wielding ruffian, the Välïümlöüt.
Instant Armor -- In five different varieties, including a "Rubber Hat" made of latex. Sequel-only.
Level Editor -- The included Critter Editor.
Made of Explodium -- The Shrapwarden. "Quite sweet little things these. Unless you shoot them..."
Made of Indestructium -- The Bane's "bouncing bombs". The constantly spammed bouncing bombs that will fill your screen within seconds. Prepare to weep.
Monster Compendium -- The Crystal Quest Repertoire of Nasties.
Mook Maker -- There's one on either side of the screen.
~~One~~ Five Bullets At A Time
Plot Coupon -- Collect all the crystals to open the gateway.
Portmanteau -- Various creature names, such as the Tentawarble, Shipnapper, Rawpuscle, and Shrapwarden.
Power-Up -- Guns and armor in the sequel.
Samus Is a Girl -- Crystal Crazy reveals your ~~circle~~ Flying Saucer to be piloted by a space cow with six legs. (Who is, of course, a girl.)
Score Screen
Silliness Switch -- The "Totally Silly" mod, in which your ship is a baby's head and your foes include dung-shooting elephants.
Smart Bomb -- The instructions liken it to "using an anti-aircraft gun to kill a mosquito."
Status Line
Super-Persistent Predator -- The inaptly named Parasite will pursue you relentlessly only to kill you with a single touch.
Black Holes Suck -- Lampshaded. "Rifts in the space-time continuum that instantly transport you from one place to another. Actually the time bit isn't really correct. Neither is the continuum bit. Or the rift. But it sounded good."
Vertebrate with Extra Limbs -- The six-legged Space Cows.