Note: This post contains spoilers for solving the side mission puzzles in Call of Duty: Black Ops Cold War. If you’d rather figure them out on your own, stop reading now!
Most of Call of Duty: Black Ops Cold War is pretty linear, but the game also includes two optional side missions you can take on pretty much whenever you feel like it. You can access those missions from the Evidence Board in the safe house, but you might not want to launch them as soon as they become available.
The two missions, Operation Chaos and Red Circus, have additional caveats that go with them. Both are about taking out Perseus agents around the world, but you don’t know the full extent of those agents’ connections when you first unlock the missions. Each has more to it: In Red Circus, you know about several double agents working for Perseus, but not their identities, and in Chaos, there’s a floppy disk with more intel that you need to decrypt. Solving both puzzles requires finding optional collectibles, called Evidence, hidden in other missions.