From https://www.youtube.com/watch?v=gWNXGfXOrro, summarized with ChatGPT 4o
The concept of a difficulty curve is crucial in game design, and "Space Invaders" demonstrates this well. The game progressively increases its challenge as the player advances, making the experience more engaging and rewarding. This gradual increase in difficulty helps keep players invested and prevents the game from becoming too easy or too hard too quickly.
"Pac-Man" introduces the idea of alternating between different game states, such as fear and empowerment. The game's design allows players to feel vulnerable while being chased by ghosts and powerful when they eat a power pellet and can chase the ghosts instead. This dynamic shift keeps gameplay exciting and varied, teaching designers the importance of balancing different gameplay experiences.