YGO Realms

This case study proves YGO Automatic Simulators are possible in Roblox, however:

If one is considering building a similar project I'd recommend finding a way to incorporate the existing OCGCore used by all the known YGOPro simulators, perhaps by connecting the game to an external OCGCore API to handle all logic and conducting duels in a separate place instance to abide by HTTPService limits.

The community isn't too fond of early YGO formats so it's not very feasible to reinvent the wheel by creating a custom YGO engine, as this game did, unless one has an immense amount of resources at their disposal, or one simply intends this as a hobby project.