https://cis.temple.edu/~qzeng/cis4360-spring17/papers/An%20Overview%20of%20Cryptography.pdf
One key is used to encrypt the plaintext and the other key is used to decrypt the ciphertext. The important point here is that it does not matter which key is applied first, but that both keys are required for the process to work (Figure 1B).
https://news.temple.edu/news/2024-09-20/flappy-bird-return-after-10-year-hiatus-true-story-behind-world-s-most-viral-mobile
It’s an endless runner game with a one-button gaming design to control a bird to fly through gaps between green pipes without hitting them for as long as you can. The gameplay was inspired by the challenge of bouncing a ping pong ball on a paddle as many times as you can.