Yeah there are some gamedev treasures in C#, owning to the fact that Microsoft created the Xbox Live Indie Games program back in the X360 era, which meant you could ship games to customers with generally little oversight and meddling - this was WAY before Steam did something similar, and even before the iPhone app store.

The catch was that you had to use C# and XNA (which was a wrapper for gaming related APIs like DirectX, XAudio and XInput, generally considered to be very good). This meant there were a lot of hardcore libs made for C# gamedev (BEPU physics is from that era, and there were things like very good UI frameworks).

Tons of games were made with XNA, and its open source ofshoots, MonoGame and FNA power some of the greatest indie hits (Stardew Valley, Celeste, Bastion and other Supergiant titles, Terraria come to mind).

Imo this is one of the main reasons Unity went with C# in the first place.