No interpretations yet? Let's have em!
You (maybe your name is Paul) were married to Esther. While driving on the way to somewhere (possibly to a port to go to the island itself) you may or may not have been drunk and a bad car crash killed Esther. The police took 20 minutes to arrive, the anxiety and guilt during that time snapped something in you. You yourself were badly injured and were taken to a hospital where you eventually recovered, and were visited by relatives.
You are an electrical engineer and you had recently landed a job to maintain the aerial at the island. After your recovery, you go there.
There was one other resident named Donnelly, a cartographer who also wrote a biography of Jacobson, a notable resident of that island from the past. He told you about the island's legends, and notably its custom of drawing large lines on cliffs to keep ships away in times of disease. Donnelly had syphilis and eventually died of it.
Then in your loneliness your mental state eventually degrades. You often travel from your residence at the lighthouse to the aerial to do your job. During one of your walks, you slip on the beach and badly wound your leg. You try to treat it with your scarce medical supplies but you get a blood infection. During the trip back you have to stop numerous times to tend to your leg. Back at the lighthouse, your delirium worsens from the blood infection and a ton of painkillers that you take.
The game starts at this point. You have decided to commit suicide and join Esther. You begin the walk towards the aerial, the highest point on the island. You hallucinate paintings on the walls: organic molecules (starting with the ethanol molecule in the lighthouse) which represent your guilt of being drunk during the accident, electric circuit diagrams which represent your job-centric existence, and various biological diagrams like neurons, which may represent some form of awareness of your mental and physical condition.
You also see passages from the Road to Damascus, a biblical passage that deals with the redemption of Saul and his conversion to Saint Paul. The reason for this particular passage is that you had been reading the Bible (it can be found near the stone circle in the 1st level) and began to identify yourself with Paul. In suicide you hoped to find redemption.
As you jump, the conversion into a bird represents you finally forgiving yourself and being at peace.
Of course, I don't believe this is anywhere near correct, specially because
presuming you lived in the lighthouse and regularly traveled to the aerial, wouldn't that be a perilous journey since it involves jumping down deep holes and crawling in caves? And how in the world would you go back to the lighthouse?
Some time after your recovery in the hospital, you attempt to commit suicide by overdosing on painkillers and have a lucid dream (which is what we see).
You might have stayed at the island and had the maintenance job earlier in your life, before the accident. You had regularly written letters to Esther back then. The island you see in your dream is not the same as the real island, hence the improbable path and random engravings/objects. The voiceover is your messed-up recollection of the letters your wrote Esther.
The interpretations of the painted signs and sentences, and the significance of the transformation remain the same.
