In a trend that started this spring, many of the 25 largest Facebook social games continued to lose users through the end of May and on through last month.

But there was some growth. Our weekly top 20 lists have consistently shown gains for any number of new and smaller developers as well as the big names. And as our Best of 2010 list highlighted, there are any number of newer titles, from developers of all sizes, that players are flocking to.

The reasons for the drop, as we’ve covered in past months, include the removal of third-party notifications and other Facebook platform changes. Developers have had to rely on less viral features like news feeds, email and advertising to reach users.

Here are the highlights for Top 25 Facebook Games for July 2010:

• Facebook farming games may have been the hype last year, but the continued plummet of Zynga‘s FarmVille – this month, losing over 7 million MAUs suggests that players are moving on; some are likely playing the still-expanding number of farming competitors.
• Zynga Poker (Texas HoldEm Poker), on the other hand, seems impervious to age, as the long-standing title actually gains 378,804 monthly active users.
• Treasure Isle is not so lucky. Though it moves up to #3, it loses nearly 3.5 million users this past month to replace Birthday Cards (#6), from RockYou, which in turn lost over 9.2 million.
• On a postive beat, MindJolt Games does quite well, moving up to #5 from #8, tallying in at over 19.3 million MAUs.
• Other Zynga titles, Mafia Wars and PetVille, continue to lose users, but to a lesser degree this month with a 2.7 million and 2.3 million MAU loss respectively. Last month, the loss was 2.8 million and 3.6 million.
• New title, FrontierVille, finally makes its way on to the list this month at #10. Having grown significantly in the past few weeks, the game is now bringing in 13.7 million monthly active users.
• CrowdStar’s trio of Top 25 apps – Happy Aquarium, Happy Island, and Happy Pets - remain in the running, but all lose users. Each game totals in at about 2.4, 7.76, and 7.64 million MAUs respectively.
• Playfish‘s older sim, Restaurant City, begins to stabalize at #13 with a loss of 800,000 users. Last month, it had lost well over 2 million.
• PopCap’s casual gone social app, Bejeweled Blitz does significantly well, moving up to #14 from #17 and earning over 10.2 million MAUs with a gain of about 400,000.
• YoVille also sees positive numbers with a gain of 45,678 MAUs.
• The developers behind ninja role-playing app, Ninja Saga also see some significant growth, moving up to #24. Previously at #25, the game totals over 5.6 million monthly active users.
• Though it was at #25 with 5,272,295 MAUs, Playfish’s new city-builder from ancient Rome, My Empire was ousted from the list by another game we had overlooked: The game show game, Family Feud from iWin and Backstage with just over 7 million MAUs who actually came in at #21.