The player controls Ori, a white guardian spirit. He has the ability to jump and climb and many other abilities. Sein can also shoot Spirit Flames to combat enemies or obstacles. Ori is required to interact with his environment as he jumps from platforms and solves puzzles. Ori is faced with enemies as he makes his way to restoring the forest. The player helps Ori collect health shards, energy shards, new abilities, and upgrades. Beside Ori is Sein, who is the light and eyes of the Spirit Tree. The game world unfolds to the player in the fashion of a Metroidvania, with new abilities allowing the player to access previously inaccessible areas.
In addition to save-points scattered in the game, players can create "soul links" at any time they choose to serve as checkpoints. The player can also gain ability points to buy various perks and upgrades, such as increasing the damage of the spirit flame.
Source: Wikipedia, Ori and The Blind Forest