Today though I discovered Awesome Blazor on GitHub and it includes 18 Blazor web games including a multiplayer dungeon which is shown (I think it looks like a bit Pacmanish personally) . Most of these are ASP .NET Core 3.1 (which became .NET 5 late last year).
Some games will use wasm (Web Assembly) while other use C# in a terminal. As a simple proof of concept but nicely done, have a look at the virtual train set online. You can lay track and then run one or more trains along it. Impressive as a demonstration of what you can do with C# and Blazor in a browser.