What games would you suggest that have LAN support these days?
While PC may be one's first thought here, I'd also be really interested in any mobile games that might leverage one's local wifi network for multiplayer.
With Goldberg Emulator you can play a lot of online games on LAN from Steam:
Steam emulator for GNU/Linux and Windows that emulates steam online features. Lets you play games that use the steam multiplayer apis on a LAN without steam or an internet connection.