Ubisoft announced that Far Cry 3: Blood Dragon sound 500k copies and caused a sale spike in the original game. It would be cool if there was an option to recreate a game that was still on the market to give it a boost. Add a zombies DLC, write more chapters and missions focusing on a side character, sign a contract with a mod author and fully implement their mod in your game (example, pistons in minecraft) . These could all be options to improve and reuse assets from existing games, allowing you to pump out titles in short time.
source: http://www.destructoid.com/far-cry-3-blood-dragon-sold-500k-copies-257147.phtml