Its been a long, long time in the making, but the day has finally arrived when we can sink our teeth into Sven Co-Op 4.0 along with They Hunger Co-Op! There are loads upon loads of new changes, features, and additions in Sven 4.0, but the team wants to point out that this is indeed a beta release, meaning that there will be bugs that will be addressed at a later date, but for the most part it's ready to be played until the wee hours of the morning.
4.0 features many new maps, monsters, weapons, and other enhancements that make the wait well worth it. The basis of Sven Co-Op is the co-op play of the original Half-Life and Opposing Force story lines with your friends and random strangers, but also includes a slew of custom maps as well. 4.0 has been developed so that you need to work together to achieve victory, so work together and work smart!
4.0 also includes "MADWHACK Physics," a physics engine that affects monsters and enemies and causes them to fly through the air when near explosions, make them take proper falling damage, and also adds physics to weapons on the ground, allows weapons to be thrown to other players, along with other physics enhancements too.
Source: ve3d.ign.com