A Microsoft community manager has teased an announcement today, resulting in a a flurry of speculation. 

Xbox's Raj Patel tweeted an image of a Roman numeral "II" surrounded by Morse code. Translated, the code reads: "Presented by Xbox 10 AM PDT 1 PM EST May 4th 2015." That tells us the when, but not the what. We can conclude that it isn't a first-party game, since it's merely being presented by Microsoft, and of course the "II" implies a sequel at work.

Several replies to the tweet are already convinced this marks the impending announcement of the next Call of Duty game. The timing would make sense--Call of Duty games are usually announced in May--and Morse code implies a militaristic game, but only time will tell.