If you like your titles rare and obscure then they don't come much better than Booga Boo The Flea which was released in 1984 by Quicksilva. I had this game on a tape of lets say not entirely legitimately accquired games and must have played this game for ages back in the day.
Basically you control a flea, the aforementioned Booga Boo and you had to get him out of the caverns past a dragon and back to the surface. I later learned that you could complete this game in less than 30 seconds if you could find the correct path and ledge to jump onto but I must say I found this game addictively difficult at the time.
The gameplay mechanics were very unique, your flea could only jump at angles and you control the speed with which he took the jump. In the caverns were lots of little ledges you could attempt to jump to but it was so difficult to get the perfect jump, and 10 minutes of trying to judge these only to fall off and back to the bottom of the cavern was really annoying.
For a 1984 game, early on in the C64's life I found Booga Boos graphics to be really colourful and rather good. The sound is pretty poor though, making no use of the SID chip whatsovever.
Once again, computer games 30 years ago were made purposefully difficult so you would replay them over and over, yet this contained so little actually playtime - is there a game out there that could be completed faster than 30 seconds!?