I seem to remember that Magnavox/Philips were sued by Atari over their Pac-Man clone called "K.C. Munchkin" and Magnavox/Philips were eventually ordered to stop selling it (which they did). This was purely because Atari felt it was too close to Pac-Man, even though K.C. Munchkin differed in quite a lot of important points from the original Pac Man.
Ok, so compare that to LadyBug by Universal. Maze game, dot eating, power-ups, etc. However, K.C. Munchkin infringed on the character design of Pac-Man: round character, chomping mouth, aliens that kind of had the same basic shape as the ghosts, etc. Magnavox was sued, Universal was not. Can't copyright/protect mechanics, just content.