Since I just recently got into the beta program, and one of the features it that you can get up to 200 players in one server, I decided to make a game called:
Baseplate, but there can be 200 players.
It is essentially a default game where you can just test how big the roblox engine will lag depending on how many players there are. I also added quests, because I think there should be something more than a empty space.
I feel like if you want to test server stability, there should just be more. If you want to try to see how Roblox performs under stressful situations, I advise you to put a lot of detail into the game itself so that the client is heavily affected. I have had around 116 players in one server in a near empty game once and it was smooth. Try adding more to your game then a few things.