The character Paul works at a pharmaceutical company and has a mug with a chemical symbol on it. This chemical shows an organic molecule (known as Perylene-3,4,9,10-tetracarboxylic Acid Diimide) that has variable "R" groups that can be altered to change the fluorescent properties of the dye . This molecular set up is known as a molecular bridge as the set up of the carbon rings allow charges to transfer across the molecule. By varying the subsituents "R", different fluorescent properties emerge owing to the charge transfer across this bridge.
This bridge is similar to the game of Dear Esther as different realizations can occur on the island. The island itself is a bridge of The Narrator's transition from one point of their life into another.
There are chemical compounds throughout the game. Some are interwoven with neuron-type images written in fluorescent paint. The first instance exists in the light house (shown at left). The presence of alcohol symbols - particularly juxtaposed with neuron images - aludes to the drunk driving that may have led to the death of Esther. Throughout the game, lewis diagrams of alcohol (ethanol) and dopamine are seen - both of these chemicals affect the brain.
Another possibility is that the carvings of neurons are relating to the syphilis infection of Donnelly, the cartographer of the island, mentioned by the narrator.
Later in the game, the increasingly delirious Narrator mentions mixing phosphorescent paint and ashes and painting symbols on the rocks. It has been suggested that it was Esther's ashes that were mixed into the paint, as it was previously implied that she had been cremated.