Leveling up is based on collecting blue orbs from completed quests and destroyed enemies. (catwithmonocle.com)
At the outset Ori is extremely limited in his abilities, as he can only run and jump, but through progressive upgrades and the help of Sein, a sentient blue orb of light, Ori becomes a force to be reckoned with. (gamingtrend.com)
In blue orb bonus stages, Sonic is running. (gamecrate.com)