If you're really stuck on a level cheat. And always start on EASY mode first, and work your way up.
If you are getting too tense, the PAUSE key does work.
If you're play keyboard, two-button firing hampers the use of the impossible pogo trick.
If you grab onto an edge, you don't have to pull up right away.
To erase the high scores, delete the CONFIG.CK4 or CONFIG.CK5 file.
Save the game. Often. You'll be glad you did.