Dead Island: Riptide, the sequel to 2011's Dead Island, was released on April 23, 2013. Having been out for less than a week, players are still searching the new island for all of its secrets. Here's what's been found so far.
Easter Egg
So far, one major Easter Egg has been found in Dead Island: Riptide. If you head to Chimamanda and search a certain hut, you'll find an end table with a coffee cup on it. Underneath is the cup is a copy of Dead Island: Riptide. Well that's pretty confusing.
Secret Files
If you're looking for more secrets to find, nabbing all 9 of the Secret Files will earn you the "Mystery Solved" trophy / achievement. Here's where to find them.
The first three Secret Files are accessed from story related areas, you'll just need to progress through the game as usual to find them.
The fourth file can be found in the BioSphere Lab. It will be located in the small room that leads to the gardens in a cardboard box on the floor.
The next file can be acquired during the mission that takes place in the WWII tunnels. It is behind a wooden panel in the room that you find the exit key.
The sixth file is inside the radio room of the military base where you video call Serpo. It's located on the desk in the corner opposite of the main screen.
The seventh is also inside the military base, on the table with the Fast Travel map.
The eighth is in Fort Henderson during "The Crash" segment inside of a wrecked helicopter.
The final file is in the Quarantine Zone behind a pile of wood boxes near the stairs from the island to the docks.
Luckily, almost all of the Secret Files can be found while progressing through the main game. However, if you miss one, you can always backtrack to find it.