A Commodore Vic 20 tape game from 1983, made by Tom Griner (he programmed a shitload of games for the Vic). The graphics are poor, but the quality of gameplay is so high.

You run from room to room, watching out for Shadow, Robodroids, Spiral Drones, and Snap Jumpers. Unlike most Vic games, this one allows more than one shot on the screen at once. It's a lot of fun to blast through a heap of those badasses.
Grab the key, run to the keyhole, smash evil, FUN!