This isn’t one particular server specifically, but rather, a whole bunch of them. This is a roleplay game mode where you can either play as a police officer or citizen. This mode is pretty cool, essentially, it’s you (players) vs bots, and the main goal of the game mode is to fight for control over the entire map by taking entire cities and towns.
Invade and Annex servers put you in an awesome co-op multiplayer experience with a ton of other players (Sometimes up to 80 or more). The first team to 100 points will win the match. The team with the most people inside the zone earns points, which contributes to their victory. Basically, 3 teams fight for control over one area and must stay inside the area to win. Because the action is so focused in one area, it is super-fast paced, intense, and honestly just a whole lot of fun.
This is a server for the popular game mode in ARMA 3, King of The Hill.