Extra Options backports the Distortion Effects and FOV Effects sliders from 1.16.2+, along with options fine-tuning what those sliders affect. Currently the two options are Control Bow FOV and Control Submerged FOV.
Distortion Effects controls the "waviness" of the portal animation and the nausea effect. At 0% there is no "waviness" or distortion; the purple swirl overlay in Nether portals will appear motionless. At 100%, distortion will work as it does in vanilla.
FOV Effects controls the amount of FOV change experienced when sprinting, on Soul Soil or Soul Sand with Soul Speed, or under the Speed or Slowness effects (technically speaking, the FOV change is experienced when the the player's movement speed differs from the base / walking speed). With the Control Bow FOV option enabled, FOV Effects also proportionally reduces the zoom of the bow drawing-back animation and the 1.1x multiplier on FOV by Creative flight.
Control Submerged FOV allows the FOV Effects Slider to minimize and disable the FOV zoom (6/7 multiplier) that occurs when the player's camera is underwater or in lava.
Extra Options is now legal for everyone to use, but abusing unintended behaviors of the mod will result in your run being rejected. Abuses of unintended behaviors include, but are not limited to:
- Measuring eyes on Soul Sand or Soul Soil with Soul Speed while FOV effects are reduced (i.e. when the FOV Effects slider is less than 100%)
- Measuring eyes underwater while submerged FOV effects are reduced (i.e. when Control Submerged FOV is enabled and the FOV Effects slider is less than 100%)
- Measuring eyes from inside a Nether portal while Distortion Effects are reduced (i.e. when the Distortion Effects slider is less than 100%)
Allowed interactions with intended behaviors of the mod that have been asked about include but are not limited to:
- Generally using reduced FOV Effects while under the effects of Soul Speed. This includes during Zero or Ground Zero cycles.
- Grabbing lava from a magma ravine while waiting in the portal animation.
If you are unsure about whether a technique that requires Extra Options would be allowed, please open a ticket.
Control Submerged FOV requires more explanation. As a feature added in vanilla not in 1.16.2 with the addition of the sliders but later in 1.17, it's effect was present in Extra Options 1.0.0 and subsequently removed in 1.0.1, but has been re-added as an option in 2.0.0. We highly recommend keeping this option off, and runs with it on will be subject to a restriction on measuring eyes underwater (under penalty of rejection). Nevertheless, this feature's re-addition has been requested and in the interest of fair competition it is usable by all.