Big Opinionated List of Game Design Mistakes

GDM 11: Never ship cutscenes that can't be paused.

GDM 10: Don't hit new MMO players with five years of cruft.

GDM 9: Never tutorial a currency without player agency.

GDM 8: Never ship a first-person view without correctly supporting inverted Y-axis.

GDM 7: Never gate the Settings menu behind gameplay.

GDM 6: Never disable player inputs without a compelling reason.

GDM 5: Never ship a game with audio and no volume control.

GDM 4: Don't tell me a currency is valuable - show me what I can buy with it.

GDM 3: Never have characters interrupt each other, unless the audio can be timed convincingly.