Synergy is a simple Half-Life 2 Modification (Mod) that enables you to play through the Half-Life 2 series and many other 3rd-party campaigns cooperatively with friends
GUIDES
FAQ
Stuck and need some help? Check out some of the questions the community have asked relating to this game. If none of these answer your problem or you want to get some tips when it comes to a particular level, feel free to submit a question of your own.