>>714242819it's tough as nails to get into, i've been trying for years.
for one there's decompilation which is manually rewriting console CPU instructions back into some higher level language. this can take years because firstly CPU instructions are not intended to be presented well to humans but are presented as efficiently as the compiler of the original source code would allow for the target hardware, secondly the compiler will make many optimizations when writing to assembly language which makes taking those instructions back into the higher level language often obtuse and nonsensical without a sixth sense for what the original intent was, and lastly there's just so much assembly to go through that writing it out back to the original language is a very very long process.
for another there's recompilation, this part skips writing the assembly back to the higher level language by hand at the tradeoff of what was written to that language again only really being useful to the original CPU as to un-fuck the auto-translated source code to something developer-malleable would take just as long as decompilation even if the upside is that it has a lower barrier to entry.
if you're really serious about getting into this, the closest you're going to get for a starting point is looking into cybersecurity, reverse engineering has a serious real world use case for cracking and patching malware so you could take what you learn from there and apply it back to video game decomps.