Der Riese Declassified:
Secrets

Remember Forever

1. Press four buttons around the map: in the room outside Teleporter Z-A, far left of the Trench Gun; far right of Mule Kick, near the coloured machine; in front of Teleporter Z-B, left of the balcony entrance; and in front of Quick Revive, between the boarded windows. Each one plays a warping sound.
2. Interact with the Samantha doll on the ground near Teleporter Z-A. It burns away in a blue flame, and four dolls appear around the map, spinning to the sound of a music box.
3. Shoot the four dolls within 90 seconds: on the shelves at the back of the Animal Testing Laboratory, on the railing above Speed Cola near the Der Riese sign, outside the map near Teleporter Z-B on the stairs by two red barrels, and on the lamp above the doorway over the Bowie Knife. If time runs out, they come back during the first 90 seconds of each round.
4. Go back to the first doll. A skeleton hand rises from the ground, takes it, leaves a Max Ammo, and the song plays.

Not So Serious Gaming and the Steam guide of STARMASTER458 put the four buttons in the main quest. Ayyden, Flapix and Tinhorn tie them to this song only, and STARMASTER458 later wrote that they were not needed on another playthrough.

I’m on Der Riese

1. Pick up three brown books: on barrels left of the Wunderfizz, on shelves in front of Teleporter Z-C, and on barrels in a corner in front of Teleporter Z-B.
2. Place them on the table of the small room right of Teleporter Z-B.
3. The table becomes a soul box: about 25 kills nearby fill it.
4. Use the table to play the song.

One of the books

A brown book lying on a barrel, its label reading RIESE.

Together, the words written on the three books read “I’m on Der Riese”. Flapix calls it more of a troll song than anything else.

Radios, film reels and key cards

The story of the map is told in recordings written by Eric Maynard, who posted them all with subtitles on YouTube the day after the release. The film reels follow Ryan Jackson, an officer voiced by PrestigeIsKey who reports on the Nova 6 project from 1968 and slowly loses his mind; the radios of the original are joined by one of Doctor Monty; and the key cards are messages about Peter McCain and Viktor Reznov.

Key cards

Two punch cards, read by the large coloured machine across from the Thompson, in the Mule Kick room: on a stack of boxes near the bridge above the Courtyard, closer to Juggernog, and in the corner by the window left of Quick Revive.

Radios

Five: in the spawn left of the stairs that go down; on the broken half of the stairs up to Teleporter Z-B; on broken shelves in the room outside Teleporter Z-B; in a furnace near the ground below Teleporter Z-A; and on shelves left of Teleporter Z-C, near the catwalk stairs.

Film reels

Four, played on the projector below Teleporter Z-A: in a broken cabinet outside Teleporter Z-B; against the wall right of the Mystery Box in the Animal Testing Laboratory; against a pallet near the electric trap at the left ground-level entrance of the Courtyard; and under the stairs up to Teleporter Z-C, in the tunnel below Quick Revive.