What’s the maximum simulation limit for game objects on modern hardware?

The limits really depend on multiple factors like CPU speed, number of cores, and how well the code utilizes those cores. For example, some games are more demanding than others. Funny you mentioned 10,000 Doom sprites—there's actually a cool video by Dave Plummer where he loads up several copies of Doom running together!

With enough engineering, you can simulate what seems like unlimited entities. Since your screen has a finite number of pixels, you can just ignore entities that aren’t in view. The goal is to create an illusion—realism isn't a necessity!

It really depends on the game's resource demands. A heavy engine might limit you to just a few characters, while a simpler one could easily handle 10,000 or more. Plus, keep in mind that multiplayer adds lag because computers need to communicate with each other, which adds overhead.

There’s no exact hard limit; it really comes down to all the little details involved.

10,000 isn't too impressive—Cossacks 3 handles over 30,000 units at once! As for multiplayer, the biggest limitation is usually network issues. In practice, you'll want to keep latency low for a good experience. If you design a space sim with realistic physics, you could potentially handle millions of players with today's tech, even if not all are on-screen at once.

What are you trying to find out? Are you just curious, or do you want to create a huge game? Maybe this is a work project?