Valve has made a clear statement that it sees the future of gaming happening on Linux, and so we have a Steam for Linux client already in use by thousands of gamers. But there’s also the forthcoming Steam Box — a set-top box-like gaming PC that is meant to sit under your TV with full access to Steam’s library of games.The success of Steam for Linux and Steam Box will come down to the support it gets from publishers and developers. How many of them will be willing to port their games to Linux rather than continuing to rely on Windows? Well, if you wanted proof that Steam Box is getting support from top-tier developers, look no further than Infinity Ward.The Call of Duty developer has posted an image on their Twitter feed and Facebook page showing a branded version of the Xi3 Piston Steam Box. No further detail is given other than the comments “Game development” and “What’s this?” sitting next to the image. The phone has been included for scale.What this looks like to me is Infinity Ward asking Xi3 for a development unit so they can start porting games and checking how they run on Steam Box hardware. In other words, they are ensuring Call of Duty games will be available for anyone choosing to purchase a Steam Box, which is a huge win for Valve if true.You may remember that Xi3 first revealed their Steam Box, codenamed Piston, back at CES in early January. It was certainly tiny, and is based off of the design of their $999 X7A performance PC. Beyond that we know very little about it, and the Infinity Ward image shows a new addition in the form of another box sitting below Piston. According to Xi3’s website, the smaller box is called APPITUR3 and is described as a “search appliance” that offers additional storage of up to 1TB. I guess Infinity Ward need it for development purposes.Regardless of when the Steam Box will be released, it’s clear Infinity Ward is working to bring the Call of Duty games to Linux, and that’s one less reason for thousands of gamers not to embrace the platform.