Rules starts off as a Space Invaders clone but doesn’t stay that way for long. Every 10 seconds, it will change into something different by randomly remixing the rules unless you clear the screen of enemies or lose 3 lives before then. It can become a “Breakout Invaders” mashup, the ship’s movement be changed (1D to 2D, reversed, sliding, etc.) or its firing (use X instead of C, the firing rate, etc.), the borders can become deadly, the ship can function as a battering ram, and more. Different combinations of the rules are chosen for each stage, which can result in a great, ok, or bad mix. Defeating all the enemies quickly enough will net a 10 second time extension and being able to loose 3 lives to end a stage helps to compensate for having to play a bad mix of rules. Space is the start button, the game starts with a 60 second countdown, and the first level is always the same and relatively easy to clear.
In all, Rules can be a quick dose of fun for those who might enjoy its novelty, and it is a nice improvement over Hideki Kubo’s older games. It’s brevity, however, is also its greatest shortcoming. All of its replay value can be used up in less than 30 minutes.