How long would it take one person to remake a AAA game from 20-30 years ago?

It depends on what you mean by 'AAA game', since I think you can argue pretty convincingly that there were no AAA games in the sense we'd recognize from modern use of the term 30 years ago.

Could you do it? Sure. Lots of people have small teams and are doing amazing work.

Is it 20-30-years-ago-'AAA'-quality work? It depends on your benchmarks for quality. Some older games are great. Others are terrible. Some genres have changed a lot. Low-poly 3D and acceptable 2D art have much higher quality bars now.

Would a game from 30 years ago without any UI/UX improvements be competitive in a modern market? It might be.

If you surf on over to r/rotp you can see a feature clone of Master of Orion 1 that's... well, it's pretty fucking fun. It's eaten a couple evenings over here, but it's still kinda clunky around the edges.

I still own a copy of SimCity 2000, my favorite game when I was a kid. Is it still fun? I think so. I think both these games have very tight designs with no fat, I think they're extremely well paced. Those are timeless qualities.

Can you produce work of sufficient quality, that is competitive in a modern market, efficiently in time and resources? I don't know you, your skills, and your ambitions. I know a lot of people bite off more than they can chew early on, because I have in the past, and now my projects are smaller and more careful in their scope.

You could burn yourself out without having a working game, too. Is the risk of burnout worth it to you? You need sleep and rest to live. The quality of your output will suffer over the long haul.

/r/gamedev Thread