The name of the company has been represented with a "0" (e.g. Zer0sum) in some cases, but the official name is with letters only.
About the company, from Iceberg Interactive's website:
About Zero Sum Games
Zero Sum Games is based in Portland, Oregon, in the beautiful Pacific Northwest region of the United States. We are an independent studio with a small and dedicated team possessing a broad and diverse set of skills. Our mission is to deliver hardcore PC games to gamers looking for depth and challenge without sacrificing aesthetics. In design and execution, we follow the craftsman’s code: measure twice, cut once. We hope you enjoy our games.