With another 675.1K units sold in May and 10.2 million in the U.S so far, Nintendo's Wii continues to be a runaway success, but third parties have yet to figure out what constitutes a hit on the platform. In the meantime, the charts are dominated by Nintendo's own first-party efforts.

In his latest industry note, UBS analyst Ben Schachter commented, "While overall hardware and software trends for the Nintendo Wii continue to be strong, we would like to see more third-party hits on the platform. To-date, Guitar Hero III, Sega of America's Mario and Sonic: Olympic Games, and TTWO's Carnival Games are the only third-party Wii games that have sold more than 1 million units to-date according to NPD, and there are many third-party Wii exclusives that have come-and-gone with minimal reaction from the market. Nintendo's share of software dollars on its platform has approximated almost 50% since the Wii was introduced, and reached an all-time high in May of 68%."

Looking at the top 20 games of May, eight titles were for the Wii. Five of those eight were first-party titles. Bottom line: if you're a third party making a game for Wii, you better have a solid plan of attack. Even Boom Blox from EA and Steven Spielberg, which got very positive reviews (8.6 on GameRankings), was nowhere to be seen in the top 20 and only number nine in the Wii's top 10 chart. We've pinged NPD for Boom Blox sales data and EA for reaction.

Update: The NPD Group has just told us that Boom Blox sold a paltry 60K units and was ranked #25 for the month of May. Considering the great reviews in addition to the hype this game received for its connection to Spielberg, we are more than surprised by this lackluster performance.

To emphasize the sad, sad state of affairs for Boom Blox, 60K out of an installed base of 10.2 million is barely 0.6 percent of all Wii owners in America.

Update 2: Although EA has yet to comment, we've now heard from NPD analyst Anita Frazier, who suggested that Boom Blox just got lost in the shuffle of great games that have been released recently.

"It's still really hard for new IP to breakthrough the noise in the market, and there has been a lot of noise so far this year. Between Super Smash Bros. Brawl, GTA IV, Wii Fit, Mario Kart and the upcoming Metal Gear Solid 4 (to name a few), there have been some really high profile game releases. The game was really well reviewed so I'm suspecting the marketing just didn't break through the clutter to the extent that they were hoping for," she commented.