Onslaught is a vehicle-based gametype that was designed and developed for Unreal Tournament 2004 by Psyonix. The object of this gametype is to capture a series of power nodes connecting your base to your opponents' base, and destroy their power core.
Overview
The most important elements in an Onslaught game are power cores, power nodes, and power links. Also frequently present in Onslaught games but not unique to the gametype are vehicles, turrets, and three additional weapons: the AVRiL, Grenade Launcher, and Mine Layer.
Power Core
Each team has one power core, usually located somewhere within the team's base. The core can lose health over the course of the game either by being attacked by the enemy team, or through draining which takes place during overtime. Power cores can only be attacked when a power node linked to the power core is controlled by the enemy team. Power cores cannot be healed by any means, so it is vital that they are protected from enemy attack at all times.
In all stock maps, the Powercore has 5000 Health, except for ONS-Dria, which has 9000. Note that these should not be hard-and-fast numbers - mappers can and sometimes do adjust this setting.
Power Node
Each map has one or more power nodes connected to the power cores by means of a power link. At the start of the game, all nodes are neutral--that is, not controlled by either team. To take control of a neutral power node, or attack an enemy node, the power node must be linked to either your power core, or a power node controlled by your team. Unlike power cores, power nodes may be healed, and building of a power node can be expedited, by firing at the node with the Link Gun alternate fire.
Most nodes have 2000 Health, although like Power Cores above, this is not a definitive, ironclad rule.
Strategies
The most common strategy in Onslaught is to rush the central node as quickly as possible and get the match down to the last node. Once it becomes a battle over the last node and your team has control of the majority of the vehicles in a map, the match is essentially over.
When SuperWeapons are enabled and a map has the redeemer, this weapon is often sought after as you can destroy a node in one shot with it. However, be careful shooting this from long distances away as they can be shot down in mid air and do no damage at all. The Target Painter is also heavily used in certain maps as it can severely damage a full health node.
Competition
In competitive play, Onslaught plays much differently. With coordination, it is actually not hard to get back the last node and start to build up a defense on many maps. One thing that facilitates this is having more than one person using vehicles, which is something that pub play often misses out on.
Scoring
Scoring in Onslaught is 2 points for a core destruction in regulation, and 1 point for a core destruction in sudden death overtime.