Guns of Fury - Endings 3 and 4 Guide
This guide will help players get Endings 3 and 4.
Retreive Anderson's Briefcase
On your way to Machine Factory and Abandoned Town make sure to grab Anderson's briefcase in the Archive Room. Shoot the ceiling between shelves 5 and 6 and the briefcase will fall down.

Archive room Briefcase.
Free Klaus and Show Him the Briefcase
After getting Anderson's briefcase, progress the story to beating Gerhard in Chateau and releasing Klaus. He will give you the Climbing Gloves after freeing him from his cell. Talk to him again to give him Anderson's Briefcase BEFORE LEAVING THE ROOM as he may move to Factory if you do so. (This does not permanently remove the briefcase from your inventory so that you may give it to Anderson later.) Normally Klaus would move to Factory to get intel on the location of the underground, but Anderson's briefcase has this intel. This will cause Klaus to move to the Sewers to find an escape route instead.

Klaus' location in Chateau after fighting Gerhard.
Find Klaus' Second Location in the Sewers
This is the location where Klaus moves. There is a vault door here that requires a special key called the Star Crest that can be found in the Jungle. IF YOU HAVE THIS KEY DO NOT PUT IT IN THE DOOR FOR KLAUS. If you open the door to let Klaus leave you will get locked out of Ending 3 where Klaus is captured. Leave Klaus here and on your way to finish the game make sure to obtain the Star Crest.

Klaus' second location in Sewers.
Obtain the Type-III Key in Chateau
Before obtaining this key you must progress the game to the point of acquiring Double Jump and Wall Jump. The Type-III Key is on the second floor above a breakable ceiling along with a Gold Trinket and Ruby.

Location of Type-III Key needed to get the Blue Vest to reach the Star Crest.
Obtain the Blue Vest in Research Facility
This location is just southeast of where we got Anderson's Briefcase. This room has a Type-III Mech that you need to set on the switch in the floor to open the locked door in the room. Once doing so, open the chest to receive the Blue Vest. This vest has improved mobility in water and protects against 'Ice' status.

Location of the Blue Vest in Research Facility.
Obtain the Star Crest in Jungle and Wrap-Up
Once you have the Blue Vest make your way to this location. The eastern most 1x2 vertical room will have a guard sleeping in a chair. Enter this room from the east, but do not approach or kill the guard. Give him time to wake up and walk over to the keypad near the rock wall. He will enter the code and the wall will open. You can make you way through the next vertical room and then the western room with the Star Crest chest. Double Jump out of the water to reach the ledge and grab the Star Crest.

Location of the Star Crest in the Jungle.
After obtaining the Star Crest DO NOT PUT IT IN THE VAULT DOOR THAT KLAUS IS AT. Progress the story until you've beaten Easton and the Titan Mech final boss. After beating the game once you should get a cutscene showing Klaus as being captured and the Ending 3 achievement. Once you've received this ending and achievement you may put the Star Crest in the vault and help Klaus escape. After doing this return to the final boss and beat them one more time. At this point you will get a new cutscene for Ending 4.