Gaming phones are commonplace now that mobile gaming has reached a level of maturity, although most half-decent phones can play modern games to a pretty good standard these days anyway. Rewind back to 2011, and the Sony Ericsson Xperia Play 1 was a unique proposition with its slide-out PlayStation gamepad and stereo speakers. A follow-up was sadly canceled, but it appears as though images of a prototype have surfaced all these years later.
We can't be certain that these images are of a real device, but XDA Developers says they come from a senior member who collects old prototypes, so there's a good chance what we're looking at is an unreleased Sony Ericsson phone. Sony fully acquired the phone maker at around this time, so it's likely the Play 2 would have dropped the Ericsson branding had it ever seen the light of day.
With Sony no longer producing a portable console, it wouldn't be a bad time to resurrect the Xperia Play line. Imagine an LG Wing-esque phone with a huge display and PlayStation controls with today's specs.