I would like you to add 3 buttons on the interface that manage the speed of the game "zero speed" => nothing moves (x0), "normal speed" => move normally (x1) and "fast speed" => everything goes x2 or x3 (or x4) faste.
Sometimes if we have fun to make big pattern, we don't always anticipate the chain reaction, like adding an arrow that moves a whole line, several addition are made without we want it, with the speed at zero we can avoid accidents.