What's the secret in the infinite purple room?

There's a secret I've had trouble finding in the purple infinite room with a waterfall :

I've tried looking in first person on every floor and wall but haven't found any instruction.

Could someone give us a hint, or an answer in spoiler tags?

2 Answers

Hint: Tilt your head the right.

Another hint:

The structure itself is a tetromino code. Decode and enter it for an anticube.

Answer:

Press → LT → A RT ↓ A ↑. An anticube will appear.

Break it down:

The shapes of the platforms are joined Tetris shapes that signify a bunch of button presses.

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