This is an uncontrollable hunk of junk, with no difficulty-curve, or any meaningful tutorial. Also one of those old games which entirely relies on manual to tell you WTH is going on, what your are supposed to do. Oh, and redifining keys - don't even dream about it. Also classic GoG-style this is missing feature (the music), and has controller-issues GoG forgot to fix. I'd be truly interrested how GoG's legal work, because it seems they grab a game from some abandonedware site, put it on their shelves, and sue everyone else who still has them.
I had the original CD version, and ... how to describe this... It is BLAND. There is nothing in this. It is a Giant Empty Space where you have like nothing to do. Oh, sure, every hundred screen you can push a button or something - I rate glitchy, uncontrollable mess of games higher than this. The real MYSTerie here is, how this thing got so many sequels.