The other answer from @[email protected] already covers most points, so I’ll just a few things:

• Most game servers out there are already built in a way to allow for easy deployment. After all, devs have to have way to test changes, so being able to run a small server locally for debugging purposes is hugely beneficial to development.
• I also can’t imagine that there’s any game server out there that shouldn’t be able to run on a single system. The heaviest one game I can imagine is Minecraft, due to the whole open world terrain generation, world streaming and physics calculations, and even that can be run off a Raspberry Pi for a small number of players.