July 20, 2026
Doomed if you do, viral if you do
Running Doom on Our Custom CPU and Going Viral
They made Doom limp onto a homemade chip, and the comments instantly turned into a nerd showdown
TLDR: A team got Doom, one of gaming’s most famously ported titles, running on a processor they built themselves, which is a huge brag in the world of computer hobbyists. Commenters loved the stunt but instantly argued over the fine print, with praise, nitpicks, and rival flexes all fighting for attention.
The makers of this project showed off something gloriously on-brand for internet tech culture: they got Doom, the legendary 1993 shooter famous for running on almost anything, to run on a computer brain they built themselves. Not bought, not borrowed — built. The game didn’t exactly sprint, more like dragged itself across the finish line, but that almost made people love it more. In the post, the team explains the mountain they climbed: their home-built processor had to deal with huge game files, extra memory, and enough speed problems to make even loading a room feel dramatic.
But the real show started in the comments, where the applause came with a side of pedantic cross-examination. One of the loudest reactions was basically: hold on, this isn’t a brand-new computer language for the chip, it’s a more standard design than the headline first suggests. That nitpick became the thread’s mini-scandal: was this a bold custom machine triumph, or was the post taking its sweet time revealing the fine print? Elsewhere, people were in full geek-love mode, cheering the use of Chisel and swapping their own “I also made Doom run on weird stuff” stories like this was an open-mic night for hardware flexes. One commenter casually dropped their own Doom-running emulator, while another said they’d done something similar and just hadn’t posted it yet — a classic “cool story, but I’ve got one too” internet move. And then came the deliciously niche debate over whether the team skipped certain math features to save space, proving once again that even when Doom runs, the comments run hotter.
Key Points
- •The authors report running Doom in real time on a custom CPU they designed from scratch and implemented on an FPGA.
- •Their earlier system could only run simpler self-written programs, and Doom required adapting the source code and adding peripherals and memory support.
- •The two main obstacles were limited on-chip BRAM capacity and insufficient CPU speed for a larger, more demanding program.
- •To address memory limits, the design integrated DDR3 and used cache in BRAM to reduce the performance impact of external memory latency.
- •The CPU version described uses a 5-stage pipeline with a unified memory interface, and the instruction fetch stage was redesigned to handle stalls and redirection with in-flight memory requests.