How do you recommend going for applying minor changes in an executable through a dll?

Question

My choice of words in the title might be poor, I apologize: english is not my primary language and I have no idea how to word it better.

I have a game executable to which I applied several changes, changes can be small replacements of integer values here and there, but also jumps to code caves, as well as adding a new section where I could put longer pieces of code.

It is essentially a mod, and I'd like to distribute it without worrying about legality; so in short I'd like to avoid distributing the whole executable and just put all of my changes inside something like a DLL. I have no experience in writing a DLL, but what I understand is that I should be able to compile functions inside the DLL then somehow call them from the executable, and my hope would be that I don't need to modify the executable itself. Can someone confirm this?

So my understanding is that for every change I made in my mod, I should copy the whole functions that contains the changes (available to me as assembly only), then I probably should compile them in the DLL.

Would that be a good way to go about it?

Answer 1

I have no experience in writing a DLL, but what I understand is that I should be able to compile functions inside the DLL then somehow call them from the executable, and my hope would be that I don't need to modify the executable itself. Can someone confirm this?

This is correct. Check out https://docs.microsoft.com/en-us/windows/win32/dlls/dllmain, common thing to do is making a new thread (CreateThread) in the process on DLL_PROCESS_ATTACH, or hook a game function.