On the Legend of Grimrock
There are lots of reviews lauding the lighting and graphics, easy user-friendly game-play, devilish puzzles that make you feel dumb and then brilliant simultaneously.
I personally am a fan of secrets you must actually locate, versus them being detected based on a skill.
Let me highlight one brilliant example of the gameplay.
Like Dungeon Master and Eye of the Beholder, The Legend of Grimrock has real-time combat. A common tactic in this type of combat is to pull an enemy into a 10' by 10' room and move to their side. Then when they walk in front of you, strike them and move to the side again. Rather then ignore this, the developers created opponents such as the crab.
Crabs walk sideways.
So those carefully honed skills you've developed are thrown out the window as you have to relearn which direction your opponents is going to move.
Then you're thrown for another loop as you discover they can walk forwards too.
Just a quick rundown to cover the bases.
There's a Dungeon Selector on the title screen!
Magic is cast using a rune system.
Four races and three classes, each with a unique selection of skills
Wonderful interface with exceptional graphics and lighting
Engaging hook leading you to seek out what's happening in the dungeon
Great monster design
Dozens of interesting armor and magic items (nothing generic here!)
DRM free, I bought it from them and they gave me a free steam key so I wouldn't miss out on achievements
You spent more than 10$ on pizza this month. Go get the game now!