Directly from the beginning of the game, you are being set up to be sad. The developers tug at all the various strings attached to all your various organs that make you feel feelings. And that's just the first 10 minutes. Even the enemies in the game have a well thought out story.
As soon as you take over control of Ori the platforming begins. Exploring the "open World" of this Metroid-Vania shows you that you will have to backtrack in order to collect items. As Ori moves along in the world, the power ups and skills are spaced out in a well thought out manner. As each skill is learned, it's reinforced for you. Then it beats you over the head. As the game moves on, it becomes very challenging, in a good way. The more skills you gain, the more Ori and the Blind Forest will make you combine those skills in order to solve puzzles, platforming challenges, and races against the clock.
Ori has a unique save system as well. You choose when to save, and when to hold onto your power that can also open doors and attack enemies. Yet be sure to save often. This is a hard game. You will die, and try again all the time. Especially in the race events that have you running and flying through a zone while water, or wind, or fire try to kill you at every turn. Memorizing the way through these puzzles is the only way through.
Controller required if you're p laying on PC. KB and mouse make it hard to aim and control the direction of jumps and attacks. But for $20 on steam, certainly worth a buy as this is bound to be in game of the year discussions come December.