#45 - Jak 2 (Kind-of-Kudos to Shogia for guessing this :P)
Often slated for being such a radical departure from its predecessor; Jak 2 was actually a massive step in the right direction for me. While I'll always have a place in my heart for simple action-platformers, the elements introduced in Jak 2 which were further refined in Jak 3 added so many different layers to the series that just made it a joy to behold and one of the highlights of the sixth gen for me.
Driving around Haven City doing tasks for various bodies was just joyful - dodging Crimson Guard being Jak's own version of GTA's cops. The increased focus on storytelling was a major improvement over Jak 1 (which wasn't too shabby in the first place); and guns added a whole world of new opportunities for interacting with Jak's environment. Possibly my only drawback from the game is the introduction of Dark Jak, which felt rather misplaced to me.
Definitely a game I'll keep returning to many, many times in the future.
