There are no guides which I assume is because we don't want everyone have it in their hacks and we see that feature as something you have to earn by being skilled enough in asm to port in yourself. Also adding it is a bit complex because you have to add: Shield art, mappings, and dynamic pattern load cues Code to use the dynamic pattern load cue Extra monitor art Additional objects for the added shields Code to keep Sonic from getting hurt depending on the enemy and shield Code to check which monitor is hit and to load the shield A flag in each enemy's code to keep it from hurting Sonic with the shield Shield ability code (optional) I recommend getting familiar with Sonic 1's code, messing around with stuff to see what they affect, and trying to accomplish smaller goals. Once you get a good idea of how the game works, you can try working on this by using what you know to edit Sonic 1's code and taking a look at the Sonic 3K Github disassembly to see how things are done there. While a lot of the code is different than Sonic 1, the shield code and object interaction routine contains code that can be brought to Sonic 1 pretty easily. Adding the elemental shields helped me improve a lot as a programmer and so I find it to be a great task to try completing once you have a good idea of how to accomplish it.