If it was proven beyond a shadow of a doubt that we were living in a simulation what would be your next move?

It wouldn't change anything because this is the reality we have. I wouldn't suddenly become immoral because there are still consequences and even if some people or even everyone but me is not real, they will still react as though they have emotions. If I hurt my wife, she would still cry. If I did something bad enough, she might divorce me. Take half my stuff. Lose some access to my kids. Those are all real consequences even if the people are simulated.
Maybe I'd be less concerned for people not immediately around me because any good simulation wouldn't actually sim everything out of range, so there wouldn't e.g. be Palestinians starving to death if no one "real" was there.
I suppose it would re-open the question of existence beyond death, but I don't think I would ultimately come to a different conclusion—there is no reason to think this experience would continue past my own death, and if I were memory-wiped and re-inserted it wouldn't really be the same me anyway, right?
If it were matrix-style there is a reality out there to experience if I can leave the simulation, I'd have some hard thinking to do about whether that would be likely to be a better existence than the one I'm having here.
- Great point! I never find this line of questioning interesting for this reason. It doesn’t change anything

But in the end it doesn't even matter

Try to access the help or stats menu.
- ↑↑↓↓←→←→BA START
  
  Sorry, does nothing mid game. You have to enter the code from the start screen to get your 30 lives.
- Time to figure out how to do some prompt injection

I would just keep living my life, it’s not actionable information for me.
- Agree. It's a lot like the 'free will' exercise to me-- an interesting thought experiment that AFAIK doesn't help too much in the actual living of a life.
  Also, I propose that we arguably already know that we're living in a simulation, and it makes no real difference. I.e., we've identified the wave-vs-particle effect, the four forces of the universe, a bunch of physical and chemical laws, and are continually refining our understanding of it all, via science, and possibly even metaphysics.
  But far as we know, it's all just building blocks, dimensions, and laws so to speak. A super-amazing simulation as it were. What's wrong with that?

Commit 34 felonies and run for president
- You're saying Trump is the 'YOLOoooo' president?

Nothing changes does it?
Also I'm not sure if I'd me more or less scared of death. If this is a simulation, to escape reality, I can't imagine how terrible reality would really be.

Remember that I'm a nihilist and shrug my shoulders.
Then start to think about how everyone else is going to react and how I'll need to plan for that.
- Then start to think about how everyone else is going to react and how I’ll need to plan for that.
  yeah that's an interesting consideration.

Try to hack it. Would love some infinite resource bug.
- Lol, what if the real world has infinite resources but only the simulation we are in has things like the absence of perpetual energy because otherwise the system would crash 🤣
- They say I can do magic, what I can do is anything.
- You missed your chance. It was called the Chase infinite money glitch.

Simulation meaning the universe and everything in it is simulated, including myself? Or like I'm jacked into a simulation Matrix-style?
The former means there's nothing to do about it. The latter means what I do here is largely irrelevant.
Big difference in response.

Does it mean anything in itself to be in a simulation?
I don't really see how that would change anything in my day to day life.

I'd give the sky the finger and then spend too much time wondering what perspective we're even being viewed from.
I'd also probably start a diary, except every entry would be: "Fuck you people for creating a world like this. Do you enjoy the suffering of countless people? Turns out God really is a prick."

Wouldn't make a difference. The only part that could change my actions would be what happens once it ends. But simulation or no I'm stuck here for however many years and have to make the best of it.

Make coffee.

Unless there is additional context like how to communicate with the outside world there's not really reason to change anything. Even if the life I love and the bonds I've created are "fake" it doesn't mean they're not worthwhile.
But if it's something like the controllers of the simulation are actively making things worse or refusing to improve things then that's different.

Jack off and do fuck all???
Doesn't change much, at least I know I only live once and afterlife is fake
- Being in a simulation would increase the viability of an afterlife. Your program could just be migrated to another "game"
  
  Umm what happens to the NPC Sims in your world
  Uhhhh goneeee
  Now imagine it being as in-depth as earth

I would have Morpheus upload Kung Fu into my brain.
- "Dammit, I hit the wrong file, you now know fung ku"

Try the ESC key.
- ALT + F4

Is there an option to leave the simulation? And could I come back if I didn't like reality?
If I couldn't come back, I would probably just stay here.
- Yes to leave the simulation you must look directly into the sun. If you can't do this, it means you're not meant to leave the simulation.

Noclipping into the Backrooms.
- why would you do that?
- Well, thats the objectively wrong answer

Have you heard of Roko's Basilisk? Basically, if we were in a simulation, it's best not to acknowledge it
- Too late.

I mean… it wouldn’t really be my move, would it?

Fuzzing inputs until I find a buffer overflow.
- Fuzzing inputs? That's just convulsing. Buffer overflow? It's called a cramp. Stop hurting yourself! 🥺

It would be an interesting fact, and I'd want to study the hell out of it, but it doesn't really change anything if nothing can be done about it.

um. look to reprogram this shit.
- L33t haxxors
- Something like this?

I think that two items would be pretty prominent for humanity:
First, if we know not just that it is a simulation but that this brings some knowledge of how the simulation's physics work that differs from our previous non-simulation understanding, how to make use of those properties.
Second, figuring out how to "break out", how to influence the world in which the simulation is being run.

Head butting bricks just became a lot more rewarding

I think a lot of unhappy people would exit the simulation.. :)

Start randomly jumping in the air and see if I can grab any unseen treats.

Click out.
- I'm always having trouble finding the click

Turn to the camera and say, "After these messages, we'll be right back."

player.additem f 999999999
- Is immediately crushed under the weight of their inventory.
  
  Dammit. I forgot we were in survival mode

If I can't determine what lies beyond the veil, then nothing much changes, does it?
If I'm presented with a beautiful utopia, or just another world that's not a hellscape that lies beyond our simulation, and then am thrust back into the simulation, then I guess I'd be less afraid of death. If I'm presented with a hellscape, then I guess I'm more scared of death.
However, if I could somehow be convinced that this is all just a simulation, but can't see what lies beyond in what is actual reality...then that's just like...knowing there's an afterlife, but not knowing if it's better or worse than this plane of existence, so it's practically worthless information.

“System call…”

I'd break the fourth wall and give thanks to the creator.
- Really? I'd ask for a reboot and say fix the damned bugs.
  Also take the cheat codes from trash like Musk.
  
  Bugs as in you found a glitch in the matrix? Or you mean like societal ones?

The Thirteenth Floor is a truly under appreciated gem of a movie, FYI

Eh. I’m still driven by pleasure and pain, so nothing really changes.

Find the command to open the console. Issue su -. Try to guess the password.

understand the rules and do any side quest that i encounter

Nothing except believing that there was a creation force that created me.