Rush is a gametype popularised by the Battlefield video game series, where one team must assault a number of heavily defended locations, while the opposing team attempts to delay the attackers from achieving their goal long enough for the game time to run out.
Typically, there are two locations that must be defended, each with a target that must be destroyed by the attacking team in order to achieve their objective. These targets can be attacked in any order, meaning the defending team will have to choose where to send their players in order to stand the best chance of protecting them. The defending team has one advantage - before the game starts, they will have one minute of time to set up defences without threat of being attacked. However, the team is also restricted to a limited number of respawns, meaning each HP lost is important. The attacking team will have unlimited respawns at their disposal, but must be careful not to walk into an ambush from fortified defenders!
The attacking team will win if both targets have been destroyed within the time limit, while the defending team succeed if they are able to prevent the attackers from completing their mission.