Alien Destroyers

As the last human left  on  the  fortress  planet of Roolfhtenin it is
your mission to  delay  the  evil  forces  of  Crabok  for  as long as
possible. You have three  laser  bases  at  your  disposal at which to
shoot the hoards, but the  longer  you  survive  the faster the aliens
will attack with dive-bombing ships.  They  have unlimited forces, all
you can do is buy time.

Once the game has loaded, press  3  to start playing. The instructions
for moving the laser base will appear on screen.