New Game runs must start fresh without a previous save. Or at least, a save without any runs/records, so you don't need to change your settings after every reset. This is to ensure every run begins with the same default set of items.

New Game+ runs are started with a 100% complete save file, with all special moves, layouts, and items unlocked.

Individual level runs can use cheats to fill up their item select screen beforehand.

There is no difference in gameplay between difficulties except for increases in damage and health of enemies, which makes "Easy" the fastest option. The only difference in Layouts are enemy positions.

RTA should be used for yourself and co-op missions, but official timing will use IGT, so bad loading times will not affect the final time.

Full game timing begins upon selecting a mission on the mission select screen and ends on the final hit of the final boss.

Co-op timing starts upon gaining control of your characters and ends upon losing control of your characters.

Individual levels use the in-game time displayed at the end of the mission.

Runs need to include a video with the time displayed clearly at the end of or during every mission, and a total sum of all in-game times must be included in the submission. You can calculate that here: http://www.unitarium.com/time-calculator

Recommended: Turn off autosaving in the settings so you won't be asked after every mission, and keep stealth kills on because the cutscenes can be cancelled, while stealth kill animations without cutscenes can't be cancelled.

Feel free to comment below and include anything you feel a new runner should know before running this game.