Synergy is a Half-Life 2 co-opertive multiplayer modification. We have evolved from multiple mods (DC Co-op 2, Dev Co-op and Tim-Coop) to offer you the greatest co-op experience. This modification strives to give Half-Life players a true Half-Life 2 cooperative experience. The mod features our own levels and the ability to play the Half-Life 2, Episode One and Episode Two campaigns co-operatively. In addition, you can add more content by installing third-party mods, such as ROCK 24 and MINERVA: Metastasis, then playing them in Synergy!
Playing Half-Life 2: Episode Two cooperatively in Synergy (Orange Box Edition).
So is this a network Co-op for 2 guys, with chat??
no u can play it with up toooooooo..................... i think 16 player
16 player with the increased_maxplayers addition, otherwise it's like 6, but if you intend to play the HL2 campaign then a few like 2 or 4 would be good. If you want to play custom however, go to a server with lots of people.