Each character in the game has their own skill tree. As players level up, they will earn skills points that they can use to purchase these skills. The maximum level is 35, which will have you with every skill in the tree. However, it is not possible to earn every single skill in a playthrough, but the game allows you to carry over the skill tree you earn in one playthrough and into another, as well as even Echelon Mode.
Skills are divided into tiers, with three skills available in a tier at first and then a single skill that is unlocked by spending 5 points in that tier. Purchasing that single skill will unlock the next tier. This is the same across all four characters.

