This could be a 5-star game, but because of the terrible voice acting (English), I had to knock a star off. It's definitely worth picking up though, especially while it's on sale. It's got a good storyline with logical puzzles. I'm running it on Win 8.1 x64 with no problems in case anyone's curious.
I probably spent more hours playing & replaying this game (with the expansions) than any other PC game, with the exception of the Combat Mission series. It's one of the few PC game CD's I still actually own. The graphics still look decent, even by today's standards. It's well worth the GOG price.