3-Check is a simple variant with one clear task in mind: Check the king as many times as you can! Normal rules apply, but you can also win (or lose!) a game by checking (or getting checked) 3 times in total.
Games can still end in the traditional ways of checkmate, stalemate and time-out.
The game can also end if a player checks their opponent's king three times.
A move that results in a double-check only counts as one check towards the "total check score."
3-Check online chess game at Chess.com