Fez is one of those must play games. It has it's own unique retro feel while drawing on past games (that weren't retro at the time). And the game is simple, no "powerups," very few timing puzzles ... it is a straight up platformer, with a twist...
You start the game innocent enough in your 2D world, where everyone actively loves being two dimensional (and will tell you just that), but that soon changes as a mysterious cube shows up and "blows your mind." From here on, you can now rotate each level by 90 degrees, with each side being a standard 2D platformer, so it is ultimately up to the player to best figure out how to reach that ledge that is just out of reach, or that cube piece that seems too high to fathom, or the door to the next level, by changing perspective; and Fez shines in it's execution of this mechanic.
Just when you think you have a level all figured out, you rotate the display one last time, and find two more doors to other levels. This explorations is what Fez is all about, and what will keep you playing for hours. The worlds you explore are always interesting, and if you are old enough to catch them, often you can see throwbacks to previous games. For example, every time you open a chest, you hear a melody strikingly similar to the one you'd hear in a Zelda game. These little throwbacks are everywhere, and Fez is all the better for it; every time I would open a chest, I would hear that tune and fondly remember my Ocarina of Time days, and that's just one example, Fez is littered with them.
Because the game is so simple, there shouldn't ever be a time when you don't know what to do. Whenever a new mechanic is added, your cube companion will tell you exactly how it works (assuming you listen to him), and often these new mechanics draw directly on previous mechanics in creative ways.
The game is also very forgiving. When you die, you're reset to the last safe platform you stood on. There is never any backtracking or redoing a level because you died midway through.
Visually, Fez is very crisp. It has the retro feel down, and only when it wants to does it break that. I can only think of one level that I didn't like visually (anyone who 100% completes the game will know exactly which one), and that was intentionally done, so again, Fez is visually sublime as long as it wants to be. The game also mixes it up quite a bit. You start out in calm, marble white and tree green filled locations, but the farther you push the more the game mixes it up, from settings like pure retro green levels (like the old 8 inch floppy disk computer displays), to pink and blue Pac-Man style levels, to haunting, stormy cemeteries. The levels are so varied that you can walk from one to another the first time and have to pause just to experience the stark changes in scenery.
The music is also great. There are levels where the music takes the drivers seat, and it's retro vibe will make you stop for a minute before finishing a level just to hear the music. Even in the most depressing/deathly of locals in the game, the music is fitting. Its hard to emphasis how well done the music is, but suffice to say, I am looking forward to downloading it soon.
I do want to note that going into the game, it seems like a pure platformer, and for most people's first playthrough, that's pretty much what it will amount to, and again, it does shine in that aspect. But, after completing the game the first time, New Game + is unlocked, granting basically the only substantive "powerups" in the game, and turns the game on its head, essentially nullifying the platforming, and giving the game a whole new reason to be played, with an entirely new dynamic... but, only if you can put the pieces together.
[Spoilers follow, and I recommend against reading this section until after your first playthrough]
While FEZ may have some light puzzles during the first playthough, puzzles and decryption are essentially the entire endgame, and they are implemented so well that most players will only see them as an artistic part of the world until they grasp the depth of the system.
To truly get the most out of the game, as I said I recommend playing though the first time clean, no internet influence about the game whatsoever (except maybe a review or two) to get a good grasp of the world and the platformer aspect. Then from the second playthrough on, I feel that some internet insight will make this secondary system appallingly obvious, and should make most players appreciate the true depth of the game. The game can be completed completely independent of the internet though (the QR codes can be bypassed, and all decryption tools necessary to solve the puzzles are in the game, though well hidden), so if you are up for a tough challenge, try deciphering the code on your own. Having just completed the final puzzle, I will say that I could not have done so without the internet, so suffice to say, it can be challenging, though this puzzle along with two others aren't necessary to 200/200 the game.
Once you truly understand the scope of this secondary system, you can realize how deep Polytron's vision for this game really was, and that made me personally love the game even more.
Ultimately, Fez shines in every way and is a must play game this year. For 800MS points, it is a steal as well. I happily give this game a 5/5!