It's called, appropriately, the Painsaw, and it's like no chainsaw you have ever seen before. Instead of chopping stuff, it runs the Doom video games, playable with an Xbox 360 controller.
Its creator is web designer George Merlocco, aka scar45, and he built the Painsaw by gutting a toy Echo Junior Chainsaw toy and stuffing it full of his own electronics, including a Raspberry Pi Zero, a 2.2" TFT LCD screen, wireless receiver for the Xbox controller and a USB soundcard.
If you want one of your own, you're going to have to do it yourself. As Merlocco points out, he build this project as a "a love-letter to Doom, the things I've learned from my Raspberry Pi(s), and a special, unique piece of memorabilia that I hope to keep forever." If you want to have a crack at it, though, he's given the project a detailed rundown on his Painsaw web page.