One of our favorite downloadable titles of 2010 is getting a second big expansion.

Toy Soldiers offered a thrilling mix of tower defense, real-time strategy, and action when it released earlier this year, and Signal Studios added to that a few months later with an expansion called The Kaiser's Battle. The success of both releases has helped to assure a long life for the game, as evidenced by a new release entitled Invasion, potentially coming to XBLA as soon as this September.

A significant change of pace for the game, Invasion introduces a number of sci-fi themed toys onto the battlefield, including flying saucers and a giant toy robot boss named Mr. Roboto.

No word yet on the cost of the expansion, but the earlier add-on went up for 400 points ($5), so a similarly priced second expansion wouldn't be surprising. You can read more about the Invasion expansion over at the Signal Studios website.