My favourite of the Trilogy because it's not as easy as the other Prime games. A great selection of upgrades, enemy and boss variety with a very dark and bleak atmosphere. Unfortunately the location variety has suffered a bit at the beginning of the game with very same-y looking areas, but i don't mind it that much. They still feel all different enough for me to not ruin my love for this game. What this game improves upon immensely compared to Prime 1 is the forced backtracking. It's basically non-existent here, making the experience much better as a result.