We lost our way as a society when we stopped making wave-based co-op modes. "Horde mode" (as popularized by Gears of War) became the hot new thing in shooters of the late 2000s, spawning unique interpretations of PvE gauntlets in everything from Left 4 Dead and Call of Duty to Uncharted and even Mass Effect.
They all ruled in their own ways, but I have a soft spot for how Bungie did it. In Halo 3: ODST, it was called Firefight: a difficult, but rewarding horde mode that leveraged Bungie's unrivaled singleplayer sandbox in the best ways possible. The mode was so popular that fans celebrated its return in Halo Reach, then grew a chip on their shoulders when 343 Industries took the reins and Firefight skipped Halo 4 to make only a half-hearted appearance in Halo 5.
