LAN/System Link/AD-HOC
LAN or System Link games are handy for multiple console homes, dorms, or the classic LAN Party. The advantage of LAN play is each player gets their own system and or screen with the added social benefit of a couch co-op like atmosphere. LAN play is most common with PCs, while the term System Link was made famous by consoles - that said - they are virtually identical in how they function. Another advantage LAN play has is that an internet connection is not required.
Examples: Civilization V, Halo Reach, Gears of War 3
Drop-in/Drop-out
Drop-in/Drop-out co-op is a handy little feature which allows players to jump in or out of a game as they see fit. While there are many implementations of this, the best is when the host player(s) don't need to stop their game in progress to allow the person to join. Some games allow players to join between levels, or wait until the player(s) hit a checkpoint. If a player needs to leave, he can drop out of the game without penalizing the other players while players that arrive late to the party can fill an empty slot up to the maximum amount of players.
Examples: Left 4 Dead 2, Diablo 3, LEGO Batman 2: DC Super Heroes
Co-op Specific Content
Co-op specific content is a specific mode devoted to co-op which does not apply to the single-player or storyline of the game. These modes are often: Survival based, where your team is set up against wave after wave of enemies. Also growing in popularity are Co-op only campaigns, where you'll play with some friends through scenarios unrelated to the main storyline or campaign.
Examples: Uncharted 3, Gears of War 3, The Darkness II, Syndicate
Co-Op Campaign or Single Player Available in Co-Op
A game that supports co-op play through the story or main campaign that's identical to the single player experience falls into this category. While the addition of players may alter how the story plays out, the bulk of the content is identical to if you were playing on your own. Obviously it's a huge bonus if all players involved get the bonuses for player (gear, achievements, saves, etc) - but it's not required. If the game doesn't offer a story mode, this option could still be check, say if it was a strategy game like Civlization.
Examples: Borderlands 2, Halo Reach, Diablo 3, Rayman Origins
Co-Op games have come a long way since our first terminology guide. We've seen hundreds of new titles appear offering unique ways to share the gaming experience in a non-competitive way. We thought it was a good time for a refresher and a good time to tweak some of the terminology used around the site to avoid confusion. With a database of over 2000 cooperative video games, there's something for everyone. Whether you use our Games Database or Search Functionality, or simply browse our Co-Op Tables for something to play - there's something for everyone.