Plutos

Plutos is a vertically-scrolling shoot 'em up featuring a succession of waves, containing what's reputed to be the first simultaneous 2-player mode on the ST or Amiga. Many of the enemies you face are waves of laser fodder with movement patterns taking them around the screen, with gun turrets and firing enemies as well, to fight or avoid. You start with 4 lives, and get an extra one (and a 5000 point bonus) after every level.

In many similar shoot 'em ups, you have unlimited fuel but must pick up ammunition recharges or increased powerups. Plutos lacks weapon upgrades, but rather inventively forces you to refuel, by shooting at posts which contain fuel (there are also bays for 500 bonus points marked out). Each level finishes with an enemy with eyes shooting at you, and from level 3 there are teeth mounted in front which fire at you.