Taulin: Sounds as if you played the Valve SP maps without the SP support update correctly installed.

Still, support for Half-Life's single-player missions is, of course, imperfect seeing as we don't have access to the map source and the maps were never intended for co-operative play. It simply allows you and your friends to play through the maps in the most complete and hassle-free way available.

The main point of Sven Co-op is its hundreds (literally) of specially-made co-operative missions, ranging from HL-universe maps set in Black Mesa to military-themed maps such as the WW2-erra AfrikaKorps (with suitable weapons for the time period and nazis to fight), on to missions where the players are adventurers gaining experience in a medieval RPG, or unlikely superheroes in a cartoon world.