How do you write patches for games without knowing the code?

Question

reverse engineering

I myself am on the web, and there is a desire to write a patch for the game, even the simplest one, but I can’t understand how, and Google doesn’t help, what tools are needed, and in general what you need to know. There is a game of the 90s in c ++ without source codes and somehow people make patches, in short, who knows, tell me

Answer 1

The case when it's probably easier to rewrite the game)))

Answer 2

There is a game of the 90s in c ++ without source codes and somehow people make patches, in short, who knows, tell me

What is the patch, what does it do?
A friend uses a disassembler and writes directly in ASM, but the game is small there. Killed several years to fully understand the logic :) But then I solved a number of problems and improved the engine a lot.
Everything depends on the goals.

Answer 3

The most "stupid" way is to analyze memory dumps and try to change the value of some variables that change with different game states. There were even special tools for this. The most difficult way is to run under a debugger, disassemble, inject your own code. This, in any case, is something that is not done at all without knowledge.
By the way, it is completely incomprehensible what "I am on the web" means, put it in human terms.

Answer 4

At a minimum, a debugger, a disassembler and minimal knowledge of assembler. It is not necessary to be able to write something on it, but you need to know the basic instructions. At a minimum, transitions (JE/JNE, JZ/JNZ).
I had nothing to do with games, but more than once I "disabled" the license key check in various programs. Back in those days (early 2000) when it was quite simple.
In any case, it is better to start with Google. Something, but there is plenty of such on the Internet. However, most of it is in English.
PS Another EXE can be packed (some UPX, DIET or other - there are unpackers) or even encrypted.