New game: Alien Intruder, a single screen jump-and-shoot arcade platformer for MS/DOS and compatible.
In space no one can hear you scream, so use your blaster instead!
Info and free downloads: https://www.usebox.net/jjm/alien-intruder/
@reidrac finally tried it. It's very cool and deceptively simple. I like that dying resets the score but doesn't put you back to stage 1: I don't really have all the time I had 30 years ago to play.
One thing I'd change: it's much more challenging to finish the game without killing enemies, so I'd invert the bonus and give points for every enemy left alive rather than killed.
@Blackthorn interesting idea!
The rationale behind that bonus is that you don't need to kill all the enemies, certainly. Some of the enemy types don't even chase you, so they're easy to avoid. IMHO killing all the enemies vs the time limit is a bigger challenge (although it only affects the score).