Bonzo is about as basic a fixed-screen platformer as you can get. The player takes on the role of Willie the Workman, navigating a screen full of ladders and platforms to collect the various boxes scattered around each level, while trying to avoid an increasing number of rotund elephant (or aardvark?) monsters trying to get you. Touch a monster, lose a life.
It really doesn't get any more basic than that, somehow even simpler than the platfomer genre progenitor Space Panic, and quite a bit less interesting. Which isn't to say it isn't challenging, though in the VIC-20 version played here that's as much a matter of the control scheme - P for up, L to go left, semicolon to go right, period for down.
In two years the game would be released for the Commodore 64 with a few improvements, including joystick control and a high score table, but the original Vic-20 release is simply dull.