Reliable & unreliable messages over UDP. Robust message fragmentation & reassembly. P2P networking / NAT traversal. Encryption.
They do offer GameNetworkingSockets though.
NOTE: The number of mentions on this list indicates mentions on common posts plus user suggested alternatives. Hence, a higher number means a more popular project.
Maybe some people out there are still in a 90 minute game against techies and they can't push the patch yet
1 project | reddit.com/r/DotA2 | 24 Feb 2022
If you want the most basic of multiplayer to your Singleplayer game, Steam Networking Messages actually works pretty nicely
1 project | reddit.com/r/gamedev | 16 Jan 2022
Introducing Epic Online Services | Game Development | Epic Games
1 project | reddit.com/r/Games | 24 Nov 2021
PC Patch Notes for patch Tomb Raider, build 838
1 project | reddit.com/r/pcgaming | 18 Nov 2021
After 1 year of hard work, a rewrite to Godot and learning networking from scratch, our game Fishards is out now!
1 project | reddit.com/r/godot | 4 Nov 2021