Overturn is one of these, a 3D arena-based robot fighting game which features not only 2-player split screen and a single player story (tournament) mode, but online play with up to four players -- truly impressive considering the game fits in only 200 blocks of memory in the Wii's internal storage.
There are a myriad of menus, but most of it is pretty easy to figure out for a non-Japanese speaker. You can set your name for solo and Wi-Fi play as well as choose your control configuration. You can either play with nunchuk and Wii Remote or both of those plus the Balance Board.
Story mode is what I spent the most time with. You have a choice of four robots initially each paired with a character who is represented by an anime cut-out drawing. You can display basic stats on your core body (head, torso and base) and then your arms which are used for fighting. Initially you have only two choices of arms, but in the course of winning tournaments you'll earn access to the same ones used by your defeated opponents. The other customisable feature is the colour of your OTM (OverTurn Mecha?): you can choose one colour for all changeable features or separately tint the base, torso/head and front and back of arms using RGB slider controls. It's a nice feature that can make an otherwise drab OTM a little fancier and distinct.
After tarting up your machine you can either do a single training battle against another robot (complete with configurable AI so you can get the hang of things without having to dodge fire) or jump right into a tournament. There are no points and no currency: you're playing for better weapons and personal satisfaction. Tournaments consist of a series of four bouts per grade. Each bout consists of an increasing number of one-on-one matches. The first is a single match; the second two, the third three matches and the fourth bout four consecutive matches against a different robot in each. Final matches in each tournament round are preceded by a little dialogue with another anime character cut-out using text bubbles.
Control is very much like Metroid Prime 3 with either the direction stick or the balance board used for movement and the view changing as your pointer moves to the edge of the screen. Even without a configurable dead zone it works pretty well. The balance board control is intuitive considering all the robots float around rather than walk on legs or roll on wheels, but honestly I'd prefer not to be standing the entire time I'm playing a game like this, so after my initial play I switched to just nunchuk and wiimote. A jerk of the nunchuk up causes you to jump into the air for a brief span of time so you can attack from above or dodge enemy fire. Z is your left arm weapon and B is the right. A+B can be held to charge up and fire a special weapon and C is used to recharge your stability metre. This metre goes down with each hit you take: when it runs out view switches to first person where you play a jigsaw minigame consisting of grabbing pieces of flashing background and putting them back into place within a few seconds. If you fail you'll fall back to earth and be vulnerable to attack until your OTM recovers, so it's worth taking the time to recharge that metre when necessary!
Sound effects are basic explosions and the music soundtrack is a nice nondescript techno. There are a bare handful of arenas which you encounter randomly: they're of good size and many offer cover of some kind or uneven surfaces. The action is fast-paced enough that you don't really have time to admire the scenery. Weapons are a range of different machine guns, mortars, laser cannons and energy swords. There's a general trade-off between weapon strength and fire/recharge rates. The robots have decent polygon counts and are nicely textured to create a pleasing look and feel for the game.
I tried to use the WiFi mode, but nobody was there; unlike other online games you can hang out without opponents and have the ability to do full customisation of your OTM as well as view leaderboards and register friends. Yes friend codes are supported, however random matches also possible with a choice of VS. or 1-4 player battle. In a nice touch pressing B brings up an entire menu of possible phrases to use whilst you're in the "lobby," unlike Tetris Party or Dr. Mario where you choose a few canned statements in advance of play and have to change them later. A nice feature of the leaderboards is that you can view the player's OTM as well as their initials and ranking -- very cool. Sadly I didn't get to see how I'd compare against another person; possibly the time zone was working against me, or like Alien Crush Returns, there's not that many people playing this game online, which is where local two-player split screen is welcome (if only the wife was more interested in fighting with giant robots than biting comments).
Of course the question you'll be asking is "will this leave Japan?" I wish I could answer that; not getting it upon release at the beginning of December was largely motivated by a hope that it would be localised. Studio Zan seems like a small outfit; the fact that all the menus and character text is in Japanese means there's a bit of localisation effort required, not to mention servers for online play. If a bigger outfit was behind it, I'd say yes, but I'm doubtful unless another publisher decides to do the job. Studio Zan should be proud regardless as they've done a game I really wouldn't have thought possible on WiiWare and done it well using less storage space than other developers have with less graphically-demanding games.
Update: UK based publisher Gamebridge will now be publishing this game outside of Japan. Happy days!