A more than classical Commodore VIC-20 game, and definitely the funniest game of the "Lunar Lander" genre. The plot for the game: Land Your Spaceship On Jupiter And Collect Points.
Even when some Commodore 64 games I found as freeware were graphics-, interest- and gameplay-wise about zilliard times ahead of this game, Jupiter Lander was great.
Why? Simple. Music and sound effects.
Try to whistle the game music to someone. Prepare for anything from grins to uncontrolled laughter. The music and sound effects of this game were just amazing, considering VIC's limited capabilities (VIC 20 didn't have a SID chip yet...) If some people say game music is not important, I want to use this game as an example that it is important. =)
The game itself was fairly simple compared to the successors: There were three areas (each more difficult than others to land on), and it even included a zoom view when your landing craft approached the landing area. Points were awarded based on how "neatly" you could land.
Grab & Emulate: