In Stax 3D you must move your paddle device left and right in an effort to catch the tiles as they drop off the conveyor belt. Your paddle can hold up to five tiles at a time. You then can drop them one at a time, in an effort to line them up in threes, either as rows, columns, or diagonals. (These are called "Staxes".)

Each level will require you to accomplish a different mission. Level one for example requires you to catch 40 tiles. Other levels will require you to complete only certain kinds of Staxes (such as diagonals).