At this stage, this case is more about an esoteric legal issue, rather than any substantive issue of infringement regarding slot machine games or video games, so I will keep it brief. Suffice it to say, the District Court (N.D. Cal.) held that Arisocrat's patent was invalid because Aristocrat did not properly revive the patent after it accidentally went abandoned during prosecution at the USPTO. Specifically, Aristocrat, pursuant to USPTO rules, requested revival because the abandonment was unintentional. U.S. Laws, however, require that the delay be unavoidable. On appeal, the Federal Circuit held that "improper revival" is not a defense to patent infrginement, and that the District Court erred by holding the patent invalid on such grounds. So it's back to the District Court for these two to now get into some substantive issues regarding patent infringements.

Read the Federal Circuit opinion here.