Skystrider: Instant purchase for me, once again! :D
The DVD version of this game was the first DVD I ever owned by the way; it came free together with the CD version in my boxed copy, but I didn't get to play it until early 2000 though, since I did not have a DVD player in my computer before then. The difference between the two versions is purely cosmetic, the CD version already has a clearly defined picture, and the DVD version takes this one step further, and also improves a bit on the audio side as well, but the CD version is completely fine, really. There is still some pixelation, but a lot less than in the previous games.
As for the game itself, I would call this the most challenging game in the series. The puzzles and hidden items are just crazy sometimes, and I often found myself going for the ingame walkthrough more than I ever did in any of the prequels. In fact, without that hint system, I think Overseer would be one of the most challenging adventure game of all time. It is a great game though; one of the last great adventures of the 90's. Just be prepared for a real challenge here, if you are determined to go it on your own without help. I would definitely recommend it, as with all Tex Murphy games!