Easter Eggs
Easter eggs are hidden references to other games.
Natural Selection 2 Poster
The Natural Selection 2 Poster can be found inside the Wreck in the Grassy Plateaus and placed inside your Seabase.
Communications Relay
A fifth message is received to the player later on in game play. The day this message is received varies. It displays: You've been down too long in the midnight sea. Oh don't you see what I mean? This message is possible reference to the song: Holy Diver by DIO.