Six Degrees of Freedom

Six Degrees of Freedom (6DOF) refers to freedom of movement in three dimensions. In the context of video games, it is a subgenre of first-person shooters (FPS) where players have complete translational and rotational control of their movement. 6DOF can be summarized as a hybrid of FPS and flight sims.

Comparison to FPS[]

6DOF games always feature the player in flight, so game mechanics and level design make much more use of three-dimensional space than FPS games. More technically, FPS games typically place the player on the ground, and therefore have five degrees of freedom because there is no side-to-side roll. Flight sequences in FPSs usually - but not always - remain in 5DOF because the player still remains upright. Additionally, while not a requirement of the subgenre, most 6DOF games do not use hitscanning and instead make projectiles' velocity a core mechanic. Combined with the high mobility also common in the genre, this interestingly makes offensive gameplay resemble a flight sim, but defensive gameplay resemble bullet hell.

Auto-leveling[]

Some people find 6DOF movement disorienting or confusing. To mitigate this, most 6DOF games feature auto-leveling, an option which dynamically adjusts the players' movement to help (or force) them to retain an upright orientation.

Motion sickness[]

The additional axes of movement can exacerbate motion sickness. Players have numerous solutions to mitigate this, but players should seek medical advice if the discomfort is too great.

Chording[]

Chording refers to moving or "strafing" (translating) on multiple axes simultaneously, for instance forward and right, which causes faster movement than is possible on a single axis. It is analogous to straferunning. Since 6DOF includes a vertical axis, a player can translate on three axes simultaneously at a greatly increased speed. Players call this trichording and consider it an advanced gameplay technique.

Not all 6DOF games feature chording, but it has been a gameplay staple of the Descent franchise since the original game. Overload itself features an option to disable chording in favor of slightly faster all-around movement speed.

6DOF in Overload[]

In Overload, the players and autonomous operators move in full 6DOF. The game uses vertical space as much as horizontal space, but most of the game's environments have an obvious floor and ceiling, making it easy for players to orient themselves. The gameplay is very similar to its spiritual predecessor Descent: the player's ship has inertia, projectiles can be anticipated and dodged, turn speed is capped, and non-player enemies are relatively slow.

Other 6DOF games[]

Wikipedia has a category for 6DOF games.