Really nails progression. Wherein some other games the game gets progressively harder, this game gets progressively easier as you learn more about the map, and gather new guns and information in a good way. Invasions can create some really unique scenarios in combat, and areas where I had trouble in at the start become playgrounds at the end where I clear the whole room by sliding, shifting, and quickly switching weapons, it makes you feel like you mastered the game, and that perfect run you need at the end was so good.