Tilted - What does tilted mean in online gaming?

Tilted is slang for "Aggravated." See an example of how people use it.
A player who is tilted is angry and, as a result, making game mistakes. These days, poker players most commonly use the term tilted, to describe players who are playing sloppily because they're salty about previous losses. However, tilted originated among pinball players.

There's A 'Fortnite' Fan Theory That Tilted Towers Is About To Get Flattened By A Comet

How to Not Tilt In League of Legends: Up Your Game And Dominate!

Winter Solstice: The Darkest Day - Space Camp Türkiye - Summer and Winter Camps for Children and Teens

Earth's Tilt Is the Reason for the Seasons!

Super Tilt Bro. for NES by sgadrat

Analyzing “Tilt” to Win More Games (League of Legends), by Jack J

Tilt Types - Riot Games Player Support

Tilt Tension HON Office Furniture

3 Tips to Not Tilt In Chess, by Nicholas Tirella