
Hard Mode Perks: Starting on higher waves gives you a point bonus, which is usually a much higher value than if you reach the level naturally.Excuse Plot: Tempest provides no reasoning behind why you're a claw-shaped ship shooting at space things in various tubes.Subverted that if you succeed in a Skill Step level (start at Level 9, for instance) with enough for more than one extra life, the game only gives one extra life.
Every 10,000 Points: Depends on the setting. Once you clear the final green level (Level 96), the next two levels (97 and 98) are repeats of levels 81 and 82 respectively, and then you're stuck in a random sequence of green levels, while the level counter is capped at 99. Endless Game: There are 16 different field designs, and once you beat 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. If you can survive into the later levels, these "starting points" become more and more infrequent- the yellow and cyan levels require beating three or four levels to checkpoint, the black/invisible levels have only two checkpoints- one at the very beginning and one at the end, and the green levels only have a single checkpoint at the first level.
If you complete a level that's designated as a starting point, you can then start a new game from there.
Continuing is Painful: Normally, new games can only be started as high as Level 9 (Level 15 in certain revisions).