The collaboration game mechanic is as the name suggests. You basically team up with other people (normally a multiplayer game) in order to complete a goal. The goals can vary from different games, it can be either a “party quest” or a “raid” or just simply an exploration. I do believe that it is possible that Collaboration can also occur when you team up with a character that is already in game in a single player game. For example in a game like Skyrim you get a follower that fights alongside you which makes your journey a bit easier.
The most common games that have the collaboration mechanic built in to the game is any multiplayer game, especially an online multiplayer game. For example, World of Warcraft. There are plenty of dungeons and raids for a player to experience, discover, and complete.
In a game that I would create, I would like to implement this mechanic by giving the player a choice of having a companion in the game, like a pet, or another non playable character.