I really want you to play this!
In fact, I can't be totally objective about it, because this game is one of my absolutely favorite ones, but I'm going to state that this the most well-made game in the whole universe.
I mean, not a single component is out or feels weak, everything is how you want and expect it to be, or maybe even beyond your imagination.
I'll try to give a clue about what the game is...
It's a looking-like-Super Mario Bros.-platformer with a deep thrilling storyline and amazing mind-blowing puzzles that that require various manipulations with time.
Our hero is able to turn the time back to the any point after you entered a stage without any limits or restrictions. Basically, you use to switch the time back if you die, so there're no game overs or anything in that kind. You don't have to restart a level when you die, you can just switch back the time to the point you can fix your faults and just move on. But what's more - in this game you use time switches for solving puzzles.
The game is separated by worlds and every world has it's unique features, like time-resistant objects; shadows, that repeat your moves, which were previously recorded by you; a ring, that freezes the time in a little range around it and more. All these things will help you to solve the puzzles and save the precious Princess...or not. The difficulty of some puzzles is pretty challenging, it can require some great patience and irregular way of thinking. Also, the difficulty doesn't really change gradually. Every world has some relaxing and insane puzzles, they're just different in the way of solving. So you won't get bored nor annoyed.
Every world has it's own atmosphere. Fantastic soundtrack and drawn game art will make you shiver every time you touch this masterpiece. Plus the storyline.
Actually, if you play through this game quickly - you might not even notice it, because the whole story is written in the books which you may just skip. But you shouldn't, really. I spent an insane time playing this game before purchasing a Steam copy. Maybe to discover its' secrets, beat all challenges, etc, or maybe just to be in-game, in this gorgeously-made world. But the best thing that I've discovered over time is a plot. It made me look at this game at the absolutely different point of view. I found out that every single world, every single piece of a puzzles that you collect, world's atmosphere and their features - everything is related to the plot, which is rather ambiguous, full of metaphors and sense.
I won't pretend to spoil about it, so just try this out yourself, it's an absolutely unique experience in the wold of games, so don't miss it and play this game right now!