Just a note about the C64 version:
Programmers did several copyprotections on this game which crackers didn't find at first.
One was the always replenishing energy on the copy, which didn't happen on the original. Another one was a door on a higher level, which couldn't be passed on the copy. I have heard there are 5 or 6 of these protections.
But now, there is a 100% crack from Remember which you can play
