When I found out that Summoning Wars, it in fact uses a freely licensed network library, I wanted to test it, but failed at compiling. Today, with fresh Subversion checkout, I succeeded and was surprised by a Diablo-rules-style RPG with 3D graphics (OGRE) a lot of dialog (hours and hours of tutorials ;) ), choices, different character classes and various spells and items.
Video: Rescuing some NPC [.ogg (shorter)]
I wonder what the network part is all about. I could imagine cooperative plot-games to be fun.. Anyways, about the net lib:
The popular network library RakNet is neither open source nor free software, as defined by OSI and FSF. However, version 2.451 (Feb 18th 2006) is GPL-licensed. It can be found via the Internet Archive's Wayback Machine [zip mirror]. The developers of Summoning Wars mirrored some version as well and even created an Arch Linux AUR package.
The owner of RakNet commented on GPL in commercial game development.