Doom was the first FPS shooter developed by id Software, and in modern times, it is often used as an example to validate some pretty weird computer builds.
Recently, it has been installed in a $49 Lightning to HDMI dongle that comes with a 400MHz Samsung SoC and 256MB of DRAM. The dongle contains this SoC because the Lightning cable uses a USB 2.0 interface that doesn't have a data transfer rate fast enough for an HDMI connection.
The data sent over the Lightning cable is compressed, then decompressed on the HDMI dongle before it's output to the display. With the SoC specs alone, it seems more than enough to run Doom, which requires an Intel 386 processor and only 4MB of RAM.
Although it can be run, the developer of this project, Nyan_Satan, has said that he will update the project to allow the game to run at a frame rate of 60FPS.