"2K Elizabeth", (Community Manager for 2K Games) forwarded me this Formal Announcement of a Hor+ Patch. To quote the page, "We always meant to have our FOV expand horizontally, but a last minute bug fix for a related issue changed this back to a vertical FOV just before ship. We feel rather silly about this, and agree that horizontal expansion is much more awesome, and that you'll have it very soon."
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Tags: wsgf, solutions, eyefinity, surround