Thank you for buying the game and the nice words!
The currently available levels are rather hard indeed. The CLIFFS level is the only level available in the IIm version (because that has to fit in 16 kB), so it couldn't be easy, otherwise the game would have been too short. Since it's difficult, it has been placed as the next-to-the-last level in the IIo version - this means that it will be preceded by easier levels. Suggestion: try also the FORTRESS level: although it's supposed to be the last one, currently it is incomplete and, for that reason, at the moment it's a little bit easier than the CLIFFS levels.
For further information, if you haven't already, please check out the notice (which, among other things, says a bit more about the levels) and the manual (which, among other things, gives a few precious tips away) included in the preview itself.
Sorry, there are no keyboard controls.