Honestly one of the most annoying and blatant examples of a game designed entirely around selling as much DLC extras as possible. The game forces requires your character to be at a certain skill "level" to continue along the main mission. To level up, you need to get a certain number of XP (i believe the number is 1,000,000 but i cannot recall exactly). The two main ways to get XP are playing missions and buying XP through the in-game store.
The problem is the amount of XP you get from the missions is insanely low and takes hours and hours of meaningless side quests that literally just end up feeling like busy work to achieve. They do this purposely so the $1-5 micro-purchases look like a cheap alternative to bypassing the hours of nonsense side quests needed to get to the main quest. You literally can't even travel to other areas of the map without being a certain level so sometimes there literally aren't enough side missions to do with your limited map space.
I remember at one point being at level up 2 levels to be able to play the next main story mission. It took me like 3 hours to take control of enough fortresses to get there.When i finished that main quest, the game said I needed to level up 6 levels for the next main mission after that. 6! That'd have taken me an entire day to level-up to without purchasing XP points. That was the last straw, I refused to play after that. The ratings online are all top tier so maybe the game is good if you are willing to pay extra for the DLC points, but that spoiled it for me.