Four-in-a-row raised into the third dimension, drop balls into a 4x4x4 cube and win by connecting four along any line, including the space diagonals.
Players take turns dropping balls into the 16 columns of a 4x4x4 cube; each ball settles on top of whatever is already in that column. A line of four of your colour wins, and lines run in far more directions than on a flat board, across levels and through the cube's long diagonals. The added dimension makes threats easy to miss, so you must watch the whole volume.
Dropping beads into the sixteen columns of a 4×4×4 cube and winning with four in a line on any level or angle is Score Four, first sold under that name by Funtastic in 1968 — Connect Four's three-dimensional cousin, later published in the UK as Connect Four Advanced.
The rules here are those rules; the cube and the gravity are both the original's.
What the third dimension does is defeat pattern recognition. The lines run through levels and along the cube's long diagonals, and the standard strategy — forcing a win by making two threats at once — becomes far easier to execute and far harder to see coming.
Fourfold is an original free browser game that lifts the classic four-in-a-row line-drop genre into three dimensions, where a 4x4x4 cube multiplies the winning lines and the ways to be caught out.