Hedgewars

Hedgewars is Worms without the licensing cost, and for a certain kind of LAN session, that is exactly what you want. Turn-based artillery games have a specific social quality: everyone watches each turn, there is always a reaction when something goes badly wrong, and the pacing gives people time to grab a drink between moves. I would not put this on as the first game of the night, but as a palette cleanser between more intense sessions it earns its place. Hardware requirements are essentially zero. If the machine boots, it runs. The difficulty ceiling is also low enough that nobody gets left behind.

Think Worms, but free and with hedgehogs. That is the entire pitch, and for a LAN party it is a strong one because turn-based games are socially loud in a way real-time games sometimes are not. When it is your turn, everyone is watching. Every shot that goes wrong generates more noise than ten rounds of deathmatch. I find this kind of game works especially well mid-session when people want something with a different rhythm, something where you can eat a sandwich between turns and still be fully in the game. Native LAN support, no cost, runs on modest hardware, and the chaos scales naturally with how many people are kibitzing from across the table.