Heh, one of the most successful modern games wouldn't exist if game mechanics could be patented or copyrighted.
Dune 2 -> WarCraft -> WarCraft 3 -> DOTA -> League of Legends.
Come to think of it, the only time Blizzard invented the whole genre was with Diablo. All their other (incredibly successful) games were refinements of prior work by other game developers.