It was the first to implement a standard online service with matchmaking, partially thanks to the built-in ethernet port. First to include a hard drive. Hell, you could rip CDs to the thing and play your own music in some games. And, I mean, fuckin' HALO, particularly Halo 2. They built Xbox Live for the Xbox 360 off of what Bungie had built for the game. Not to mention the 'standard' controls that literally every shooter on consoles has started with Halo. Hell, it was the first console that supported HD resolutions. The PS5 only exists in the world that the original Xbox helped make.