Based on what I remember from my first completed game on Klik & Play back in the mid to late 90's. Multiple controls and rules for levels.
Collect money from your housemates to steal a spaceship to get back home to [not included] stop evil aliens from taking over. Eventually led to two completed sequels and one that was in the works. All of which have since been lost.

Level 1:
8-way movement = Move
Collect all coins to advance to next level.
Collision with enemies restarts entire level.

Level 2:
Platform movement = Move
Button 1 = Jump
Get to LEM to finish level.
Getting hit with asteroids restarts entire level.

Level 3:
Controls in-game
Button 1 = shoot
Shoot all asteroids to complete level.
Collision with asteroids restarts entire level.

Level 4:
Same as last level.
Get to Mars to finish level.

Strange monsters are replicating every few seconds. Destroy them quickly with your two machine guns!
CRAP! Forgot to load them first! Grab ammo from the nearby containers.

Up/Down = Movement of both guns.
LMB on crate or barrel = load 50 bullets into a single gun.
Nothing as long as ammo is in = guns shoot automatically.