CheatEngine is a memory scanner and debugger that is particularly suited for this task. We decided to get a bit of a kick start by using CheatEngine to find interesting code paths based on the games UI.įirst up was finding out what code was responsible for the ammo count. Sometimes, getting started is the hardest part.

However, any patches or binary modifications had to be implemented using Frida, and not by manually patching chocolate-doom.exe. Using tools such as IDA Freeware, CheatEngine and WindDBG was considered fair game though. This meant that reverse engineering efforts would be a little harder, but that was part of the challenge and learnings we wanted. Once extracted, chocolate-doom.exe was a stripped PE32 executable. The chocolate-doom source code is available, however, we did not want to reference it at all. We downloaded chocolate-doom for Windows from here, extracted and sourced a shareware WAD to use. The chocolate-doom project exists and aims to be as historically correct as possible while still working on modern operating systems. The original Doom game was released in 1993, built for OSs a little different to what we have today.

The source code for our cheats live here if you want to play along, or maybe even contribute new ones :) The setup

Toggle cheats just like how they behaved in classic doom.

Increment everyone’s health for the amount it would have gone down for.

Increment your ammo instead of decrement it.

We managed to get cheats working that would: The results? Well, a video of it is shown below. For SenseCon ’19, Lauren and Reino joined me as we dove into some reversing of chocolate-doom with the aim of recreating similar cheats. Remember iddqd and idkfa? Those are two strings were etched into my brain at a very young age where fond memories of playing shareware Doom live.

Doom 2019 cheat engine