A developer could hack into the Apple Lightning to HDMI dongle and run Doom directly on the accessory. According to nyan_satan’s comments in the YouTube video (h/t MacRumors), the $49 Apple Lightning Digital AV Adapter features a custom Samsung SoC with a 400MHz ARM Cortex-A5 core and 256 MiB of DRAM.
The dongle should be enough to run Doom, which requires a 386 processor and 4MB of RAM. Apple put an SoC inside the dongle because the USB 2.0 protocol that Lightning used did not have the bandwidth required to run HDMI. So, it compressed the data from the Lightning device and then used the chip inside the adapter to decompress it for viewing on HDMI displays.
