Pity the sequel to a perfectly good puzzle game. Its core idea is already established, appealing, and therefore limitlessly enjoyable. The sequel can only refine it, add to it, or broaden its player base with bonus modes. And it can't disrupt the balance of the original concept too much, unless it wants to stray into the gimmicks and meddling that lead to Tetris 2, Tetris Worlds, or Tetris Splash.

And the first Puyo Puyo Tetris was a perfectly good puzzle game. It was perhaps mercenary in its merging of the two most popular puzzle games on the planet (no offense, Yoshi's Cookie fans), but it worked well. Puyo Puyo, created by Compile decades ago, requires players to bunch together blobs while Tetris, even older and more revered, demands they work odd-shaped blocks into complete lines. Yet they're both part of the falling-object school of puzzle design, and that was good enough for Sega.

The game can switch between Puyos and tetris blocks during a match, pit someone's Puyo skills directly against a Tetris player or vice versa, or combine the two in Fusion mode and have blinking globs and spinning Tetrominos (that's the official name for Tetris, just in case you want to impress someone) on the same playfield. The mixture requires Puyo Puyo to be faster and Tetris slower, yet the concept proved fun the first time around, particularly with four players involved.

How does Puyo Puyo Tetris 2 follow that up? At first glance, it's very close to the original. Puyo Puyo Tetris 2 presents the same modes largely unaltered: Swap once again requires you to juggle two games at once, Big Bang is a rapid attempt to clear the screen as skillfully as possible, and Fusion just mixes it all together in a hodgepodge of blocks and blobs. The latter is both the most original and the messiest part of the whole crossover. Tetris is a game of speed and precision, requiring you to process and clear lines as quickly as possible. Puyo Puyo is more gradual in planning and payoff, rewarding players who build a mountain of blob creatures and then set off a chain reaction that dumps a lethal dose of rocks on an opponent's half of the screen. Fused together, they're chaotic. But for those who dislike such experiments, other modes preserve the gameplay styles separately, and discrete vanilla Puyo Puyo and Tetris modes are available right from the title screen.

Puyo Puyo Tetris 2's most elaborate new addition comes in the story mode, finding its entire cast wrapped up in a crossover that players uncover one stage after another of jovial excuses for puzzle duels. Puyo Puyo emissary Ringo is relentlessly enthusiastic and embraces the nonsense that comes, while Tetris space traveler Tee is the straight-man to it all. Together, they bond with other weirdos in cutscenes that swing from adorable to tedious. Puzzle games are seldom about stories and memorable characters, and those that are usually borrow them from other sources (such as Sakura Wars: Hanagumi Taisen Columns or Super Puzzle Fighter II Turbo), but Puyo Puyo Tetris 2 has sense enough to garb itself in self-aware humor and competent voice acting. The motifs it overuses are at least amusing ones: describing onomatopoeia like "slightly less confused thinking sounds" and trotting out the reliable humor of creatures like O and Carbunkle bonding through Pokémon-esque gibberish.

That story sets up the biggest new gameplay feature of Puyo Puyo Tetris 2. Switch mode puts players in control of a team of characters, each with a different ability. Some heal the player's life bar, some wipe out rows of junk blocks, and so forth. Unlocking new characters in story mode gives you more party members to customize and level-up, and the duels follow an RPG-like system of hit points. Instead of aiming to fill your opponent's side to the top, you're better off dealing out as many combos and lines as possible, preferably wiping out their health meter in a matter of seconds. It's an aggressive twist on the usual back-and-forth of puzzle games, and a largely welcome one.

It's a shame that Puyo Puyo Tetris 2 couldn't delve further into that RPG element. The story mode's wide cast of characters asks for something a little more substantial, if not a dungeon-crawler full of random battles similar to Compile's old Mado Monogatari series. Even the cast list isn't much large, though it's nice to have Carbuncle as an individual character. One couldn't expect a smorgasbord of classic Compile cameo from The Guardian Legend and MUSHA and Golvellius, but it could use a few major players from Sega—you know, Yoko from Last Bronx, Big Landman from Burning Rangers, Scooter from Alien Storm, the snail from the Master System's built-in maze game, and maybe even that hedgehog thing.

What's there in Puyo Puyo Tetris 2 is enticing: a bright, simple vision of two worlds colliding in all sorts of ways. It's hard to fault the multitude of special modes or dislike any of the characters, but it also invites questions as to why Sega couldn't build more on the first game's sturdy bedrock...or at least refine everything to perfection.

In fact, some small changes aren't for the better. The overall controls feel sightly slower than the original Puyo Puyo Tetris, and it primarily affects the Tetris side of things. Characters appear in little background animations when players land certain moves, but that occasionally bogs down the actual gameplay—a strange drawback considering the game's relatively basic look and presumably simple mechanics. These might not be gamebreakers for messing around in a multiplayer party, but it's a rough deal for the dedicated, competitive Tetris fan.

Indeed, Puyo Puyo Tetris 2's upgrades are less technical and more superficial: a lightly amusing story, customizable teams of characters, and a new round of cute animations and fully voiced dialogue (though the characters no longer charmingly intone “SAY-GAHHH” when the logo appears). Is that worth a full new game for the players who already have Puyo Puyo Tetris--or, more cynically, for those who could get the original discounted now that the sequel's out?

Puyo Puyo Tetris 2 is a strange sort of successor. It's certainly not a bold, potentially fan-alienating change to the formula, but neither is it a complete improvement. The colorful story, numerous frills, and Switch mode progression amount to a plus for any fan of Puyo Puyo's aesthetics and characters, so it's odd that the game seems lazily assembled and disappointing that it isn't more ambitious. It leaves Puyo Puyo Tetris 2 an enjoyable puzzle game, yet it's not everything a good sequel should be.