Clash Royale
In short
A real-time strategy mobile game developed by Supercell that blends card collecting with tower defence.
In plain words
You build a deck of special cards to summon troops and spells. You use these to attack your opponent's towers while protecting your own. Matches are fast and usually last only a few minutes.
A simple example
A player might use a Giant card to soak up damage while deploying Archers behind him to destroy a tower.
Why it matters
It is a major title in the mobile gaming industry and a successful spin-off of Clash of Clans. It helped popularise the competitive mobile esports scene.
Easy to mix up
Do not confuse it with Clash of Clans, which focuses on base building rather than real-time arena battles.