Custom RISC-V soft-core FPGA retro gaming system runs 32 games at 45 FPS

Hardware hacker M_Jagadeesh97 has built a complete retro gaming system around a custom-designed RISC-V soft-core processor synthesized for the Terasic DE0-Nano FPGA board. The system leverages 32 MB of external RAM and drives a 64x32 pixel display, a resolution chosen to match the original DOOM's aspect ratio while maintaining playable 45 FPS performance on the constrained hardware. The project includes a bootable game launcher with 32 titles and implements a Wolfenstein-style raycasting engine from scratch.

The writeup documents the full stack from bare-metal CPU design through video signal timing, making it a rare end-to-end public accounting of RISC-V system bring-up without fabrication access. The DE0-Nano's Altera Cyclone IV FPGA and commodity components keep the build accessible, and the addition of a small display yields a portable demonstration of what low-cost programmable logic can achieve with substantial custom engineering effort.

FPGA platform and RISC-V implementation details

• FPGA platform: The RISC-V soft-core targets the Terasic DE0-Nano development board, which uses an Altera Cyclone IV FPGA, with 32 MB of external RAM available to the processor.
• Display subsystem: Video output is limited to 64x32 resolution, a deliberate constraint that preserves the 4:3 aspect ratio of DOOM and similar vintage games while enabling the 45 FPS target on minimal hardware.
• CPU design scope: The project encompasses full bare-metal RISC-V CPU design, including instruction implementation, system timing, and video signal generation from the ground up.
• Graphics engine: A Wolfenstein-style raycaster was custom implemented for the platform, demonstrating practical 3D-ish rendering on a resource-constrained soft-core processor.
• Portability: The completed system integrates a small physical display and achieves portable form factor, with the DE0-Nano and commodity components keeping replication cost low.

Why it matters

This project contributes a documented, end-to-end RISC-V system design that others can replicate or extend without semiconductor fabrication access, reinforcing the open ISA's role in education and hobbyist hardware. The combination of open RISC-V instruction set architecture with affordable, widely available FPGA dev boards lowers barriers for embedded systems learning and retrocomputing experimentation outside ARM-licensed ecosystems.