Looks like we might have jumped the gun when we declared Square Enix's mystery game would be another Crystal Chronicles. Turns out, the company is working on a browser-based side-scroller for Yahoo! Games Japan, and they're calling it Crystal Conquest. And here we were thinking handheld or mobile...
In their announcement, Square refers to Crystal Conquest as a "real time battle strategy game," but the FAQ describes a team-based side-scrolling brawler. The final game, due out this summer in Japan, will support 40-man battles, in which two teams of 20 face off in a flashy exchange of summons and other abilities.
The whole "strategy" aspect just refers to the game's card-based skill system; before each fight, players can assign skills to their fighter by putting together a Skill Deck and Wild Card Skill Deck.
Alpha testing is currently set for April 12-16, and sign-ups start April 9. Check the official site if you're still curious (and can read Japanese). We'll just be in the corner, concealing our excitement-turned-disappointment.