Match-three is the most-played puzzle format in the world, and Candy Crush is the game that made it a phenomenon: swap two adjacent candies to line up three or more of a colour, they vanish, everything above falls, and sometimes that fall clears more by itself. King released it in 2012; this page runs a browser match-3 in the same mould, playable without an account or an app.
The depth comes from the specials. Four in a row makes a striped candy that clears a whole line; five in an L or T makes a wrapped candy that explodes twice; five in a straight line makes a colour bomb that removes every candy of one colour. Combining two specials is where the big cascades come from.
It is a browser match-3 in the same style, playable free with no account. King's official Candy Crush Saga is a separate app with its own levels and progression.
Match five candies of the same colour in a straight line. Swapping it with any candy clears every candy of that colour on the board.
Yes — it is a light 2D game that runs in the browser with nothing to install, with mouse or touch controls.