Kairo is an abstract first person puzzle/exploration game where you work your way through a geometric world to complete what are initially seemingly arbitrary tasks to accomplish a goal which is not immediately apparent. It is obtuse, but stylistically so, and easy to get lost in. I recommend walking around and exploring before diving in too deep, but when stuck in any given room, you can go into the menu and choose up to three Hints to help point you in the right direction - this is the saving grace of the game, as they progressively give more direction without telling you what exactly to do, so you're never actually LOST, it can just feel like it at times.
The controls are a little "floaty" - they don't feel as tight as most other first person games, but due to a lack of combat that's not necessarily a problem, just takes some getting used to. The graphics are simple, but very effective - the spectacle is quite impressive.
In addition to the normal gameplay goals, there are a series of 18 runes to find hidden about the game, one "go back and find later" puzzle where, after you exit an area, something secret opens up which you can find, and three exceptionally hard "did you notice that one little thing elsewhere? Interpret it in this abstract way here!" puzzles which you might need to look for external guides for.
The game doesn't take too long (aside from those harder puzzles) - 3-4 hours should probably be enough to get through it.
I had a good time with it. It's probably not up everyone's alley, but if the above sounds interesting, check it out.