Doom was from the early 90's. The internet wasn't a common thing, so TCP/IP was not as thoroughly established then as it is now.

In the early 90s IPX/SPX was more common for LANs than the IP stack. It required much less configuration. Managing IP addresses in the days before DHCP was a hassle, while IPX just used MAC addresses directly. It also was just a simpler protocol. This was in the days of DOS where the driver had to run as a TSR the lower 640KiB memory area, so the driver size mattered.

In the later 90s IP pushed it out, partly due to Novel Netware fading away, and partly because IPX didn't scale to large networks the way IP can.

Great response, thank you :)

Googled tsr, terminate and stay resident if anyone else is reading this.

One other question, if a dos game used TCP/ip, would the developer have to write their own ip stack? Presumably dos didn't provide any of this?

Yeah, IP wasn't batteries included in the OS until later. I believe there were a variety of library venders but honestly don't know for certain.

Thanks

Fun fact about doom IPX is 1.0 absolutely spammed the heck out of the network finding peers. Most colleges had big problems days after its release because doom was DDOSing the network. They quickly patched it but patching wasn’t as easy as it is now.

Funny, that's actually how Jay Cotton (co-creator of Kali) learned about Doom and what led him to start exploring the network side of gaming.

There's a decent interview with him that relays the story: https://episodiccontentmag.com/2016/08/26/kali1/

that comment brings smile to my face and tears to my eyes :)))

Because "internet" barely existed at the time doom got out. People played multiplayer games mostly in the same physical room.