If you are using Livesplit on Windows, Into the Breach has an autosplitter available to assist with letting Livesplit handle the splits for you. This guide will help set up the autosplitter based on how you have your splits set up for each of the main categories.

First, enable the autosplitter. If you go into "Edit Splits", then enter Into the Breach into the Game Name dialog box, you can then select "Activate" to enable the autosplitter.

Next, head into the autosplitter Settings. By default, the autosplitter is set up as follows:

This means that the autosplitter will start the timer on pressing Start in the hangar, will reset the timer whenever you re-enter the hangar while the timer is running, will stop the timer when the final cutscene starts, and will split the timer whenever you leave an island. This is ideal for most users for 2-Isle%, 4-Isle%, Glitched% or any of the Hard-Mode categories.

The other options in the autosplitter settings are ideal for other categories, or if you want more granularity in your splits. For example, if you want to have sub-splits for each mission and the two phases for the final mission, you can enable all of the options. For each item you enable, just ensure that you have enough splits in the list to account for all of the options.

An important thing to consider is that if you are running a category where you play through multiple timelines, such as All Squads% or 100%, you should disable the Reset checkbox, otherwise, the game will reset whenever you enter the hangar to select the next squad.

If there is a particular use case you wish to use for your splits, you are welcome to ask me specifically either here or on Discord (R30hedron#9520) for help.