Schizm: The Mysterious Journey

It's a Myst-like. You can switch between two protagonists on an alien world (which really, really does looks alien) who need to find out what happened to all the scientists. Backgrounds all seem to be pre-rendered, so 180° looking around only works in those places intended. They used real actors for intro/cutscenes.

Tried playing it years ago, got frustrated and quit. Like the dude above me said it's a Myst alike on an alien world, with very abstruse puzzles. Though, the real reason I'm commenting is to let folks know that you can actually buy it on GOG.

I haven't played this myself yet, but I watched a longplay of it on Youtube a couple years ago and I thought it was fantastic, but the music is especially where it's at--I was already listening to the soundtrack when I saw this game in the list! The puzzles do seem overly complex, and I couldn't imagine getting through it myself without just following a guide the entire time (hence why I watched the longplay), but I loved the visuals, the overall world-building, and that amazing music so much that I immediately bought the game on GOG when I saw it on there. (I also found the dual protagonist approach to be unique, but that could easily just be due to my ignorance of similar games. This one is pretty old, though!)

One caveat: I noticed this game seems to have an odd predilection for dubbing over every actor in the game with another actor who doesn't "look like they'd have that voice", if that makes any sense to you. Some people try accents that I don't think ever work, while other times it almost seems like the actor is just doing ADR for themselves, but the tone they take doesn't match the facial expressions, so it comes across like they didn't even know what they looked like while reading the lines. A very strange experience, but due to the narrative in Schizm, it surprisingly didn't detract from my  experience like the bad acting in so many other FMV-reliant games. I was easily able to imagine the Game Dungeon episode on this while watching the longplay for the first time. I highly recommend it (with a guide) if you're into the atmosphere the screenshots and OST give off.