Quake was the only game to support DOS and Win95 with TCP/IP multiplayer in one executable—deep dive explains how id Software did it

https://www.tomshardware.com/video-games/quake-was-the-only-game-to-support-dos-and-win95-with-tcp-ip-multiplayer-in-one-executable-deep-dive-explains-how-id-software-did-it