Although once little more than an academic endeavor, the RISC-V architecture is slowly replacing applications that typically went to ARM. Also, some microcontrollers have chips that run this open-source instruction set now, and we expect it to grow in the future because it does not require the licensing of an ARM or x86 chip. [M_Jagadeesh97] is ahead of the curve with this retro gaming system built on a custom designed RISC-V system.
Most of us, presumably including them [M_Jagadeesh97]do not have access to chip manufacturing tools, but what we can get all of different FPGAs. This RISC-V CPU is built on a Terasic DE0-Nano board with 32 MB of RAM available, and boots to a starter with 32 games available. There are some limitations with this low-power system, which were largely solved by limiting the display to 64×32, allowing it to keep the same aspect ratio as the original DOOM as well as the same aspect ratio for many of the older games, while still maintaining 45 FPS.
The project write-up goes deep into the design of a system like this, from the bare metal, the CPU design, the timing of the video signals, and how to wolfenstein-like raycaster. After adding a small display, it also looks quite portable and is an excellent demonstration of how powerful inexpensive boards like this FPGA can be with the correct effort.