Chain
Four in a clump and the whole stack goes.
Chain
Four of a color touching pop, and so can whatever falls in after.
Orbs fall in small pieces — two of them, sometimes three in a line or an elbow. Four or more of the same color touching side to side or top to bottom pop, everything above them falls into the gap — and if that landing makes another four, it pops too. Each link in a chain is worth double the last one, so the big scores come from building a stack that collapses on itself rather than clearing as you go.
On a computer, once a game is running the arrow keys take over: left and right slide, up spins the piece, down hurries it along, and space drops it the rest of the way. On a touchscreen, drag left and right to slide, tap to spin, swipe down to drop — or use the buttons. Nothing shows you where a piece will land, so spin it into shape on the way down. The board pauses itself while it is off screen, and while it is paused or waiting to start the arrow keys go back to scrolling the page.
Fewer colors means clumps form on their own; five means you have to plan for them. Your best score for each setting is kept in this browser.