Blind-running this game on Nightmare was one of the hardest yet fun things I did on my life, dying over and over again to the point that each battle took about half an hour, and each stage at least 2 hours, but never feeling unfair or exhaustive because learning the core game loop of managing resources and getting to know that every single weapon and modification has its uses and synergy with other guns/mods, all seamlessly making me a better player while never making any future fights any easier than the last.

Truly a masterful action game, sadly, it also made every single other sub-genre of FPS feel boring.