As Alexander enters North Wind, he gains the ability to look back in time to see for him self what happened on the ship that went missing, the ability is called Mental Echo. This ability is triggered when Alexander find and approaches dead crew members scattered around the ship who suffered a gruesome and horrible death during the survival of the freezing temperatures. He then enter their bodies when they were still alive and acts out their final moments. He then has the ability to physically change the present by travelling back in time and altering the memories of crew members or even creatures on board the ship. So when Alexander exits the dead ship crews bodies successfully and re-enters his own body, the corpses have disappeared, meaning they survived whatever horrible death they originally suffered. If Alexander fails rescuing a crew member he will return to his own body and the corps will be in the same place as it was when Alexander first saw him.
When Alexander enter the Mental Echo he then has a chance to see how it was on the ship before the accident, but also during the accident. So he first handedly gets to see what went down there before the ship went missing. So the source to clearing up the mystery hidden in the game is the dead bodies of the ship's crew and the Mental Echo.
Alexander discovers a lot of weird and frightful things on the North Wind. And he quickly learns there are creatures there out to hurt him. Alexander finds a lot of handy tools to protect himself with. A good couple of melee weapons, but also some typical World War II era guns and rifles he can use to defend himself. Alexander of only an explorer and not a gunslinger, so the basic handling of the guns can seem a bit awkward -- in a realistic sense, and not as a game breaking factor.
Another important factor in Cryostasis which directly affects Alexander is the freezing cold in the North Wind. It's so cold there even the warm clothes Alexander wears from the beginning of the game isn't enough for him to keep warm, so he constantly seek new heat sources to stay alive and not freeze to death. He's general "health" is based on these heat sources as well as not taking any damage from whatever threats is hiding aboard the ship.