I believe it was a sidescroller, but I wouldn't bet a single cent for this after all these years. The only certain things are:
-it was C64 game and I played it some time around 1990/1991, but game itself was proabably older, maybe 1985/1987
-the main character was some sort of funny-looking monster with little trunk (slightly similar to
Gribbly)
-i remember that he moved ONLY to the right via jumping and afair he couldn' be stopped, there were various obstacles along the way like stones or maybe spikes, this I don't remember clearly, all you could do was to press the key in correct moment to make him jump higher or sth
-i remember only two screens: first one was an ascent to the top of the mountain and next one was the descent, there were no platforms of any kind, only ground and obstacles
-so first screen looked a bit like this:
