Why haven't they created a smartphone hybrid with gaming controller?

[Grant]

We already see smartphones that can bend, and smartphones that have an additional smartphone attached to it. But why hasn't anyone come up with a smartphone that has a controller built in? Like one that can pop out from a hidden spot in the phones case. I would have thought someone would have come up with a controller/smartphone hybrid. Is there any kind of gaming smartphone like this out there? I feel like there was one already, but can't remember what it was called.