Zero Order Hold
Introduction
Zero Order Hold is an ambitious campaign-style mission for Halo Infinite made in Forge. Players find themselves captured aboard a Banished airship in flight and must escape and capture the airship from the inside. The map implements a unique wind physics mechanic and emphasizes tight, varied encounter design. It's also considerably longer than its predecessor. It was later selected by Halo Studios for its Forge Features column.
The map and associated mode are available on Halo Waypoint and will be added to your in-game Bookmarks list once bookmarked on the website.
Ideation and Design
The map originated from the idea that the Sonic the Hedgehog and Halo series have similar level design principles in terms of creating spaces with distinctive personalities. The level Sky Deck from Sonic Adventure is one of my personal favorites from the series with the player climbing around the outside of a massive airship, and I thought it would be an interesting challenge to translate the concept to a Halo mission. I took additional inspiration from Halo levels set aboard spaceships to settle on a prison break scenario with a mix of interior and exterior combat.
Setting the map on a moving airship also allowed me to explore a new mechanic for Halo campaigns: wind physics. Physics has always been a major throughline in Halo's gameplay, but it is rarely experimented with in encounter design. For Zero Order Hold, I implemented a custom system simulating the effects of drag along the bottom and top of the airship. Along with smart use of particle effects and moving objects below, this creates a convincing illusion of movement and puts a twist on gameplay by changing how the player and enemies interact with the environment.
Achieving all of this required thorough planning, so I spent some time prototyping the mechanics in a test map and planning the environment before starting on the mission proper. A prelude on land was initially planned, but was cut for time and pacing.
Players battle along the underside of the ship in Zero Order Hold.
Sky Deck from Sonic Adventure was a major inspiration.
Scripting Logic
For Zero Order Hold I was able to mostly reuse the campaign framework I created for Inclemency with minor extensions. The dynamic difficulty system from that map was also retained here.
The bulk of new scripting work came in implementing the wind system and associated effects. Wind physics are not a native part of the game, so it took multiple days of development to reach the flexible volume-based system used in the final product. The result is extremely functional, affecting all physics-based objects within a wind zone as expected, but performs best when playing the game locally instead of online. I additionally created a system to slide scenery objects beneath the ship to create a sense of a moving environment; this creates some networking overhead, so the effect is only enabled when in view.
Wind physics may help or hinder the player.
Final Design
Breakout
The mission starts with players trapped inside of the ship's brig. By sneaking through vents they can escape their cell and into the rest of the airship. While brief, beginning the level this way neatly establishes the narrative setup without needing dialogue or cutscenes, which are unavailable in Forge. Use of the motion tracker and cover can allow players to clear this section without being detected by enemies at all.
Party Crashing
The vent crawling eventually drops players right into the middle of a bloodsport arena just as a match is about to start. Aside from conveying that players are no longer expected to be subtle, this adds some personality to the level. The absurdity of there being a combat arena on a military airship is a fun play on the Brutes' character and unceremoniously dumping players into the most exposed position possible is a memorable practical joke after the previous stealthing. The encounter also provides players with good close-range weapons for the next section.
Players explore more of the ship after exiting the arena. This area revolves around an outer hallway. Enemies guard the other end and there's little cover to use, but rooms to the side provide a safer flanking route through a firing range and an armory. The armory connects back to the brig to establish physical continuity. After clearing the hallway, players continue further towards the front of the ship and fight their first high-ranking enemy to cap off the first act of the mission.
This section aims to recreate the feeling of Pillar of Autumn, the first mission of the series and one which mostly consists of room-to-room combat. In Zero Order Hold, large side rooms are used instead of that mission's narrow serviceways to better fit Infinite's more acrobatic combat.
Going Under
Streams of air through a vent system revealed by the previous encounter guide players to the front of the ship with a dramatic reveal of the terrain passing beneath them. The bridge is directly above, but the only way forward is below.
The wind mechanic is introduced here as the following encounters take place on platforms and bridges suspended along the bottom of the ship. The wind affects everything: players, enemies, grenades, dropped weapons, and other physics objects are all blown around by it, forcing players to adopt different tactics for this area.
To ease players into the effects of the wind physics, the first encounter has them moving towards the rear of the ship with the wind to their backs. This makes it almost exclusively beneficial for them by preventing enemy grenades from reaching their platform and allowing for large jumps over gaps. The next encounter has players moving parallel to the wind, making it a more neutral element in the sandbox. These arenas are designed mainly for medium range engagement to contrast the previous sections, but aggressive use of the wind can get players up close and personal if they desire.
The section ends with players using a Man Cannon to launch themselves to another series of platforms with an elevator at the end. The wind blows them off-course directly into the elevator, making for a fun scare.
Elevator Action
The elevator lifts players through a frenetic encounter in a spiralling serviceway. Small squads of enemies on each level pressure the team from all angles, but the elevator's ascent provides moving cover through the center and the enemy squads gradually move up along with it to ease the intensity towards the bottom. At the top of the shaft is a large, vertical chamber with a Jetpack Brute and other forces to fight before ascending further upwards with some platforming.
Surface Tension
Players emerge on the top of the airship for a series of challenging encounters. Having already reached the back of the ship, they now have to move to the front with the wind working against them. The arenas in this area also introduce new uses of the wind physics as a wave of junk is launched towards the team and two story arenas encourage more maneuvering. At the end is a Hunter pair. In the main campaign, Hunters are only met after acquiring the Thruster Pack to circle around them more effectively. Players have no equipment in Zero Order Hold, so they must instead utilize speed from the wind to hit the Hunters' exposed backs.
New Management
Finally, players reach the ship's bridge through a vent in the ceiling. The last encounter is a battle with the bridge crew and waves of reinforcements until the captain emerges as the final boss. The captain (a boss from the official campaign) wields a Gravity Hammer and moves quickly, forcing players to dodge around the multi-leveled bridge while dealing damage. With more players, additional bosses are added alongside the captain to split the team's attention. The mission ends when all enemies are defeated with the ship having been fully captured.