You're actually serious? I never considered just asking for it lmao(I mean I didn't know I needed source code until now XD). On the likely chance I won't receive the source code, how would you go about reverse engineering it?
That is not an easy task.
Have a look at some recent reverse engineering projects:
https://github.com/n64decomp/sm64 (complete)
https://github.com/orgs/zeldaret/repositories (oot mostly complete, others in various stages of completion)
These are huge projects, taking a skilled team years of work to complete.
That is not the only way to reverse engineer a game though. They went for making 1:1 "identical" source code (not actually identical, but functions identically and compiles to an identical ROM)
If you don't care about 1:1 accuracy, then many other projects went the other route, recreating the engine from scratch as closely to the original as possible, but using all new code. This is arguably easier as it includes less reverse engineering work, but risks resulting in having bugs that were not in the original game, not having bugs that were in the original game (might not matter to most but matters to speedrunning folks or those who just enjoy messing around with game glitches), or some things simply not working as expected when compared to the original game, which takes additional work to fix and some issues may never be fixed or there may be missing features.
Examples of this would be NXEngine (Cave Story)
https://github.com/EXL/NXEngine, ScummVM (various classic point and click games notably ones from LucasArts), OpenRCT2 (Rollercoaster Tycoon 2), EasyRPG (RPG Maker 2000/2003) or any of the games on this list:
https://en.wikipedia.org/wiki/List_of_game_engine_recreations
Still, that's no small task either and takes skilled people. And I am guessing you're not a programmer/developer, or you would understand how big of a task this would be. Which means you have no chance of making it happen, you'd have to learn how to code first and practice until you're skilled enough.