The Brief: To be tilted means to be angry or upset.
Tilted is often used to reference the negative feelings one experiences when they are losing or performing poorly in a game. It’s a common video game slang term, but can also be used more broadly to describe being upset. Being tilted or “on tilt” can affect performance in a game. The phrase “don’t tilt” is sometimes exchanged between gamers to encourage their teammates to stay focused and avoid tilting.