Gears of War is arguably most famous for popularizing cover-based shooting and gun/chainsaw hybrids, but the franchise owes its longevity to the inaugural chapter's multiplayer—a vital component that almost didn't ship with the game in 2006.
You may remember that Gears of War was one of the Xbox 360's early marquee titles. Delays pushed it back, and back, until Epic Games and publisher Microsoft pegged it for a holiday 2006 release. In an interview with IGN that mostly centered on Lawbreakers, lead designer Cliff Bleszinski shared an anecdote that showed just how determined Microsoft was for the cover-based shooter to leave the nest.
"It was just like we always say even with [Lawbreakers], 'We're building a freeway while the car's going 9,000 miles an hour on fire. We were under intense pressure from Microsoft to get this game out for holiday, doing the E3 demos and all that, and they didn't really think the cover-based gameplay would be any fun [in a multiplayer setting]."
Bleszinski went on to describe some the ideologies that informed Gears' multiplayer. He originally wanted players to earn in-game credits and buy weapons and ammo between rounds at a store for example—not surprising, given that Bleszinski hasn't been shy about taking cues from Resident Evil 4, which places a mysterious merchant before major encounters so players have ample opportunity to buy new guns and upgrade trusty sidearms.
Furthermore, many of Gears' early maps had a Counter-Strike-esque feel to them, but Epic producer Rod Fergusson—now heading up Gears of War 4—proposed planting strong weapons around the map so that players would have reason to play aggressively rather than hunker down behind conveniently placed walls.