Those who remember the SNES port of Doom probably remember the game being a cumbersome pixellated mess. But what made it special was the fact that head programmer Randal Linden was able to eschew the use of the game’s original engine, and instead build a whole new game engine (Reality) in order to get the game running on the console.

And with the SNES version nearing its 25th anniversary, Linden has chosen to release the game’s source code to show just how he was able to accomplish the task of bringing one of the most popular first-person shooters of all time to the SNES. It’s worth nothing that Linden was able to do all of this himself without the help of the programming genius of John Carmack and id Software.

For you technical junkies, Doom on the SNES used 216×144 pixels for the 3D canvas, using halved vertical resolution (columns are rendered twice, effectively making the canvas 108×144 pixels), at 10 frames per second on average. Many levels had to be cut in order to fit the game on a cartridge, as were most of the monster poses and sound effects. Floors and ceilings had to be rendered as solid colors to increase rendering speed.

Miraculously, the game supports the SNES mouse, the Superscope, and even the Xband modem for online play (remember those?).

As for Linden, he would go on to help create Bleem!, the infamous PlayStation emulator that was actually sold in stores back in the late 90s.