Here's a real blast from the past! Back from a time that the term 'indie' hasn't been invented by the hipsters (or journalists? Who cares anyway!). Back when the Internet was but a dream, and to get any news one had to buy magazines (in my case, imported from other countries) with coverdisks filled with Public Domain (and other) stuff. And in the first coverdisk I ever got (ST User, June 1990), this game was inside:
and what a great game it was (and still is)! Simple shooter, easy to pick up and play, but becomes very tricky after a couple of levels. Basically you have your ship that can only go left/right and waves of enemies come at you. You have to clear each wave completely before you can progress to the next, and with the enemies firing and moving frantically about it can become really hard.
I keep coming back to this game once in a while, in my opinion one of the best PD releases for the Atari ST. Download and play on your favorite emulator already :).
P.S. My brother woke up one day in 2003 and decided to port it to the PC (and I had to rip the graphics for him :P)!