Here's a simple bit of alternative-deathmatch kind of fun for LANs, powered by Newton.
Must say that keeping several Newton worlds in sync across a network is not particularly easy, but this works pretty well as long as all the machines can keep up with the rendering load.
http://www.newrevolution.orcon.net.nz/ballance-c3.msi
Let me know what you think - and also if you're interested in using the C3 engine for something of your own design, we can sort out some license terms for you.
-Chris