CastleStorm, by Zen Studios, is getting a new update called Free to Siege. Now you'll be able to challenge yourself to see how long you can last against wave after wave of pillaging vikings. Each wave survived will net you some fame and Pearls.
You can now train your troops and upgrade your weapons to level 20. And you'll need them to work toward taking first place on new Survival Mode leaderboards.
The Survival Mode update is available for download now, and you can get CastleStorm for free on the App Store.