No Mercy in L4D2
Playing the No Mercy Modified campaign, one of the versions of NM ported over to L4D2. It works surprisingly well online.
Instructions are here:
http://nekoarcnetwork.com/l4donl4d2/i...
You can also find just a .vpk file here, but there will probably be some bugs:
http://www.l4dmaps.com/details.php?fi...