Assassin's Creed is another series just begging to be a card game. The war between the Templars and Assassins would be yet another interesting and engaging game, allowing for all out card wars between and across the many different time periods that the games take place in.
The stories that have already come to pass only cover a few parts of history, so the card game could cover everything else that the video games have not touched. In addition to providing an almost limitless amount of content, it allows for multiple expansions to be released (which is good for the developers), along with an endless possibility of timelines to take advantage of. AC the card game could be just what the franchise needs to be revitalized!