The Xenosaga series is rooted in grand mythology and even grander scope. While not directly connected to the critically acclaimed Xenogears, the two series share thematic material. Predictably, fans' expectations were astronomically high, and while Xenosaga Episode I and II were divisive among players in many ways, most agreed that the story was still worth following. It came as a relief, then, that Xenosaga Episode III: Also sprach Zarathustra defied expectations and capped off the series in spectacular fashion. The biggest issues plaguing the first two games, namely Episode I's heavy dependence on cutscenes and Episode II's convoluted gameplay, were largely eliminated in Episode III. Although the series was tragically truncated (spanning only three games instead of the projected six), Xenosaga Episode III managed to provide a satisfying conclusion to one of the most complex stories ever told in a video game.

This is the hack & slash that launched a thousand titles. Diablo II recently celebrated its 10th birthday (original release date: June 29, 2000), but it's still getting play, and fans eagerly await the third installment on its release date of "when it's ready." This game took the original Diablo and cranked everything up a notch – it was loved by many for its online play, but even those who prefer a solo experience could play it over and over again, hoarding loot and trying out different builds of their favorite characters. One year after the game's release, Diablo II: Lord of Destruction expanded on the already stellar gameplay in so many ways that it was obvious Blizzard was listening to their players. New classes, a bigger stash, runeword crafting... the list goes on and on.

And if imitation is the sincerest form of flattery, then just look at the number of copycats this game has spawned. After 10 years, it's still one of the most likely games for hack & slash RPGs to be compared to. Even its MMO cousin, World of Warcraft, took a number of cues from the lessons Blizzard learned in Diablo II. If you've never played Diablo II, and you like quick, fun action, give it a shot. Any PC these days can run it, and you can carry it fully installed on a USB stick for a few stolen minutes of thumping demons wherever there's a free computer.

The original Kingdom Hearts came out of left field, and seemed like a crazy idea – a sort of "ice cream on pizza." But millions of copies and several sequels later, it looks like the idea wasn't so crazy after all. Perhaps it was something about seeing Donald and Goofy point at stars in awe as they blinked out of existence and worlds ended, or the fact that these two light-hearted characters we all grew up with were facing the danger of a seemingly unending dark force. It helped that we experienced this unique new universe where Disney characters mingled with the likes of Squall and Cloud for the first time right alongside the hero of the series, Sora. Many of us grew up with the Final Fantasy series just as we did with Donald and Goofy and Disney, so to see pieces of our childhood coming together like this was a surreal experience – one that has become wildly popular in the years since. The music was a memorable fusion of Disney classics and new tunes by Yoko Shimomura, and the gameplay was the brainchild of Square Enix darling Tetsuya Nomura, who arguably owes much of his popularity these days to Kingdom Hearts. For these reasons, the original Kingdom Hearts has earned a place on our top 20 RPGs of the decade.