The lighter mode removes the sanity meter, saves automatically after each solved puzzle and allows unlimited manual saves. The intermediate mode keeps sanity while retaining puzzle autosaves and unlimited manual saves. The original experience keeps sanity, disables autosaves and limits manual saves. Choose with your preferred retry rhythm in mind.
Journal
Revisit your journal after finding a document or solving a mechanism. Compare the new objective with the rooms you have already inspected before retracing the whole island.
When the island becomes dangerous
Seek secure shelter when something is prowling nearby. Laudanum restores sanity. Avoid prolonged exposure to the experiments and plan your next objective before leaving a safe spot.