After 25 years, a series like DOOM is guaranteed to collect its share of fun facts and interesting trivia. Thankfully, you don’t have to be the world’s most dedicated fan or a development insider to learn some of the coolest stuff about this franchise – you have us!

DID YOU KNOW:

Damage in DOOM (1993) is calculated like dice rolls in a tabletop RPG

Members of the Slayers Club may already know Dungeons & Dragons’ influence on the original DOOM. However, not many also know that the shooter that started it all has another tie to pencil-and-paper roleplaying games: its damage system.

You ever notice that sometimes a Zombieman goes down in two Pistol shots, but other times it’s three? It’s a small difference, but this is because damage from the original DOOM’s weapons and demon attacks are calculated using random values and constants – or to oversimplify it, a dice roll.

Using a 256-byte static table, DOOM (1993) features a pseudorandom number generator that breathes life into the game, be it variable enemy behavior, light flickering, sounds effects and attack damage. To see how DOOM runs without it, Software engineer Johnathan Dowland recorded a video of the game running deterministically and the results are fascinating: