You'll need to do all of these things to unlock everything in the album:
- Unlock every character except Esseb Tarosh
- Kill every monster 50 times
- Finish a game with every pod
- Reach floor 24 with the Drill Pod
- Finish a game with Sasha Chokyo, Wes Davoun and Zugma Walker
You'll also need to unlock these biography secrets:
Australium!
Bug vs. Bugeater
Clash of Heroes
Downfall
Whiskey Tango Foxtrot Interrogative
Who Talked?
With Honor!
For the biography secrets requiring 3+ heroes, start your game in the Armory Pod and pick who you need.