DOOM Finally Crashes After Two and a Half Years of Running Continuously
By Tuin
Sep 18, 2025
Someone recently carried out an experiment to see how long DOOM could run without crashing. The game in question was the 1993 classic. It ran on an ASUS MyPal A620 Pocket PC, using a Windows Mobile port called WinDOOM. The device was powered continuously via a homebuilt UPS setup to avoid interruptions.
The test was done by forum user “minki” on the LenOwO board. They used the demo loop mode (the attract or demo playback) where the game repeatedly runs and restarts demos. In each loop a built-in counter called “gametic” increments. That counter is stored as a 32-bit signed integer. Because it never resets in that mode, it slowly climbs toward its maximum possible value.
At 35 ticks per second, it takes nearly two years for that counter to reach its limit (2,147,483,647 ticks). In practice the game ran for about two and a half years before it finally crashed. The crash was due to integer overflow of that counter.
This kind of bug is not unique to DOOM. Other retro games have similar overflow issues under continuous runtime. For example Crash Bandicoot 3 and Final Fantasy IX have global timers or clocks that overflow after around two years, causing strange effects or unlocking hidden outcomes.
The experiment highlights how older game engines used simple timers or counters without anticipating a scenario where people might leave them running indefinitely. While not a flaw in regular play, these overflow bugs are a fun glimpse into how software behaves when pushed beyond expected limits.
The test was done by forum user “minki” on the LenOwO board. They used the demo loop mode (the attract or demo playback) where the game repeatedly runs and restarts demos. In each loop a built-in counter called “gametic” increments. That counter is stored as a 32-bit signed integer. Because it never resets in that mode, it slowly climbs toward its maximum possible value.
At 35 ticks per second, it takes nearly two years for that counter to reach its limit (2,147,483,647 ticks). In practice the game ran for about two and a half years before it finally crashed. The crash was due to integer overflow of that counter.
This kind of bug is not unique to DOOM. Other retro games have similar overflow issues under continuous runtime. For example Crash Bandicoot 3 and Final Fantasy IX have global timers or clocks that overflow after around two years, causing strange effects or unlocking hidden outcomes.
The experiment highlights how older game engines used simple timers or counters without anticipating a scenario where people might leave them running indefinitely. While not a flaw in regular play, these overflow bugs are a fun glimpse into how software behaves when pushed beyond expected limits.