Sandbox Environment
A sandbox environment is an isolated area where you can test code, without worrying about how it’ll affect anything else. Typically, it’s a virtual machine where you can experiment with or test your game.
Create a separate testing network
If you’re making a multiplayer game, you’ll want a sandbox environment for your servers. You’ll want to test whether the server-side image runs properly and that you can connect to it from a client. This isn’t to stress-test the system (you’ll do that later), but to make sure that no bugs cause a major crash.