Tilt originally means to cause to slope or lean. In gaming slang, it refers to a state of mental or emotional confusion or frustration in which a player adopts a less than optimal strategy.
Common usages of tilt:
1. "I'm on tilt" - meaning I'm frustrated and playing poorly
2. "Don't tilt" - advice to stay calm
3. "Tilted" - describing someone who is angry or frustrated
Other meanings include:
1. A sloping position
2. A medieval jousting competition
3. A pinball machine feature