I just finished Rhem. I loved it. this is the best game that I have played in a long, long time. It took me back to the reasons that I first started playing adventure games.
As background I'll say that I started, as I guess many of us did, with Myst. I generally like first person, mouse-driven, puzzle-oriented games including Myst, Riven, Exile, Qin, the Zork games, Timelapse, etc. There are a few third person games like the Broken Sword games that I've liked a lot. I am not big on character interaction games where you talk to everybody about everything and have to help the conversation along by clicking on the next item. Then, usually, you have to talk to everyone again whenever something else occurs.
But back to Rhem...A huge game world to explore and puzzles that were pretty difficult. I solved what I considered some real toughies but had to go to a walkthrough for some. This is not rare - I probably save enough not buying hint books to pay for my internet access. Most of the puzzles were logical and there were clues although some were obscure. I couldn't believe how many new and huge new areas kept opening up as I solved some of the challenges. This is the first game in a while that I have stayed up late to play because I just had to test a new hypothesis on the solution to a puzzle. I thought the graphics were quite good - maybe not as high-tech with water effects and the like as some new games, but the system reqs. weren't that high either.
I can't wait for Rhem II!!