The Artifact: The illustrations on the side of the original cabinet show actual monsters rather than the abstract squiggles that serve as the enemies/targets in the actual game. This was because they were designed and printed at a time when the plan was for them to look like that. By the time the developers threw in the towel on making credible-looking monsters with the game's vector graphics, it was too late to change them.
Asteroids Monster: The Tankers will split into two Flippers when shot at. Later on in the Yellow levels they can split into Fuseballs and Pulsars.
Endless Game: There are 16 different field designs, and once you clear the last level, you're sent back to the first but with a difficulty increase and the color palette altered, coloring the fields in the next loops red, yellow, cyan, black, and green in that order. Once you clear the final green level (Level 96), you're stuck in a random sequence of green levels on Level 97 and beyond, while the level counter is capped at 99.
Smart Bomb: The Super Zapper (renamed the Super Tapper in the sequels). You get one free use each level, and it will eliminate every enemy on the field automatically. Try to use it a second time and it will result in a weaker blast that only kills one enemynote Usually the one closest to the top or the strongest enemy currently present at the time of use.
What Could Have Been: Tempest was originally a game called Vortex. Instead of the player moving, the playfield moved and the gameplay was modeled on Space Invaders. This was scrapped due to motion sickness; in turn, this fact might have inspired the Polybius legend.
The sequels (Tempest 2000, Tempest 3000, Space Giraffe and TxK) provide examples of:
Animal Motifs: A recurring theme in the sequels as with many of Jeff's projects is the mention of ungulates such as bulls, cows, llamas, ox, and sheep.
Camera Screw: Specific to Space Giraffe, where the camera is positioned to create blind spots in your vision (i.e. columns perpendicular to the screen). Additionally, there is camera spinning starting on stage 49.
Damn You, Muscle Memory: In TxK, the in-between level sequences where you can gain a few bonus points by lining up the particle with the center of the screen, you're using reversed flying controls (where up makes you go up and down makes you go down). However in the "Fly through Rings" bonus stages, you use normal flying controls (where hitting up makes you go down, and vice versa).
Everythings Better With Llamas: the games contain multiple references to llamas and other ungulates, in the form of psychedelic imagery (during the game) and text (the names of some levels and some entries in the high score table).
Game-Breaking Bug: TxK has one on the form of the player randomly moving even when no input is being touched on the left analog stick. This mostly seems to happen when you're in the middle of exiting a level. What's that? A Spike? Have fun with your ship randomly decide to run into it even when you're in a lane that's 100% clear of obstacles.
Another one happens in the "Stay on the Green Path" bonus stages. If you're moving with the left Analog Stick, the particle you're moving will suddenly lock in place as you're moving it. If it happens near the end, it will without a doubt screw up your entire run, denying you the 50,000 point bonus.
Have a Nice Death: When you die in Tempest 2000, you can read on your screen what caused your death (e.g. "Caught you!" "Shot you!" and so on). This was changed since Tempest 3000, where you just get different sound effects depending on how you died.
Interface Screw: Thanks to the camera in most of these sequels, you usually cannot see enemies or enemy projectiles that are in the same lane or directly adjacent to you. In TxK you can turn the camera left and right by tilting your device, but nothing happens if you tilt it up/down, which would be the more useful view angles to look around in.
Self-Imposed Challenge: In TxK, beating levels without ever jumping note In TxK, you can no longer gain score if your ship is in mid-air, compared to past installments that don't have this rule in place.
In a Google Tech Talk video, Jeff Minter had a discussion about his games created at Llamasoft. He discussed Space Giraffe, where he designated level 64 "Flumm Ox" as that one level. "If you get to level 64, I guarantee the first time you get there you would just go 'What the smeg is going on there' and you'll die." He then plays through the level. In particular, Level 64 is a 4-pointed star, with the tips being tight together. Enemies are generally slow, and everything has a psychadelic shading to look different. The level being with a large number of "danger!" announcements (those enemies that reach the top shoot two horizontal bullets), followed by spheres, flowers that extend past the limit. The combination of these makes the level difficult, at least according to the author. Choosing Space Giraffe NUXX on startup removes the color shift that plagues level 64, and renames the level to "Stargoat". The NUXX option tones down the background and psychadelic effects, but doesn't change the overall difficulty of the level.
Warp Zone: In Tempest 2000, if you succeed in any of the bonus rounds, you will gain a 20,000 point bonus and warp ahead five levels. The warp doesn't happen if you're nearing the end of the game.
TxK changes this to instead give 50,000 points, but without the warp.
What Could Have Been: Jeff Minter's plan was to have Tempest 2000's soundtrack in Space Giraffe. This did not happen because, in his words, trying to get the rights back from Atari was hell.
Xtreme Kool Letterz: A Tempest 2000 review on Youtube mentioned that, had it been actually made in 2000, it would have been called "Tempest 2K". So in 2013, Jeff Minter made another Tempest sequel and called it TxK.