This is not a game you can complete by chance or effortless tries.
You have to understand its core mechanics, the architecture of each level, the tricks you'll need to complete the hardest paths, and after all this understanding, you will need and WANT to master all of it.

The "wonderful" part is that the game doesn't just throw you in a world of spikes and blood. Well, actually it does, but gently. You start from levels which is almost impossible to fail, yet everything in the game reminds you that anything less of a "perfect run" (double S rating) is worthless, that your times are awfully high.

You will then take a look at some videos or replays.
If you feel ashamed and want to get better at it, well, you're in for a gaming experience like few others.