Replaying Pokemon White 2 on Challenge Mode... man, BW2 is something else. It's a game where you think "oh yeah, that's really good," but you don't realize
how good it is until you replay it. The presentation, music, mechanics, content, story... it all comes together into an incredible package. I've replayed a lot of Pokemon games this year, but ending on BW2 is a very high note. This is my first time playing Challenge Mode and it really does a lot for replayability, especially the Gym Leaders which can be surprisingly tough.
While Platinum is still my favorite game, largely because it has my favorite region and batch of new Pokemon, BW2 really feels like the ultimate culmination of the design philosophy GameFreak had during the DS years. It's harder to analyze my enjoyment of it on paper because of a distinct lack of nostalgia (came out while I was in college) but every time I revisit it I just have a really, really good time. On the other hand, despite my nostalgia and love for gen 2 and its remakes, on HGSS replays the faults become more and more apparent, while the opposite happens with BW2. Gen 2 had the biggest impact of any of the Pokemon sequels, but things like leveling and pacing leave a lot to be desired, whereas even deep into the postgame BW2 is still challenging and engaging the player. It's a shame nothing released since BW2 has lived up to its potential.
I don't think it's a bad thing to enjoy something because of nostalgia though. Nostalgia doesn't have to be a dirty word. Taking nostalgia and impact into account, I'd rank BW2 and HGSS nearly the same in enjoyment and appreciation, but the more I replay them the harder it is for me to make the argument that HGSS is
better as an overall package. (Walking Pokemon certainly goes a long way though!)
Also, I think BW2 does a really good job winning people over who weren't over the moon with BW. A lot of a person's enjoyment of BW will rely on how they feel about the story and focus on new Pokemon. BW2 does the smart thing by de-emphasizing the story and adding 150 old Pokemon to the region in addition to all the other great content and improvements.
Platinum > BW2 => HGSS > BW > rest is in constantly in flux but that top 4 feels pretty solid at least.
But seriously though, that music. I don't know
what the composers were snorting during gen V, but I want some. Easily the best OST in the series: