Whether your production budget is reaching for the skies or buried under a mountain of paperwork, you need a hook for your video game to really take off. Newer genres like first-person 'walking simulators' and roguelikes fall back on exemplary stories or loot-grinding gameplay mechanics to hold you in their midst, but there are many age-old staples of marketing that work wonders if the right amount of care and attention is thrown their way.
Every long-standing, easily-recognisable character or gameplay aspect had to start somewhere, and although such a quality can receive quite the boost of popularity depending on various factors at time of release (Sonic the Hedgehog releasing amidst the "Radical, bro" 90s, for example), it remains that if you're then going to frame your entire PR campaign around such a thing, you'd better deliver on it.
Now, take that ideology and apply it to the ludicrously budgeted likes of the modern era, and wasted potential can be just as crippling as an outright broken game. Anticipation and hype are forever through the roof if you're a gamer, and when those emotional investments you're making don't pay off, well, you get these...
Whether you agree with the fan consensus on Halo 4 as the 'one that ruined Halo' or not, it nevertheless put the franchise to the back of many gamers' minds, especially seeing as Bungie had left after Halo: Reach to pursue what would eventually become Destiny. 343 Industries were never going to achieve the sort of global media-enslaving might we saw when Times Square itself shut down to reveal Halo 3, but they certainly gave it their all, doubling-down on marketing geared towards a major conflict between series-regular Master Chief and relative newcomer Spartan Locke.
Multiple teasers were shot in live-action, showing alternating setups where Locke would have gotten the better of Chief, and vice versa. The whole thing was set up to allude to a major untold story point, something "personal" that Chief had supposedly done to Locke, with the idea being that Chief was on the run for an act he didn't commit or do.
In reality, this just wasn't the case. It turned out the much-touted Locke versus Chief 'bout of the century' came from the former wanting to find the wayward Cortana, thereby disobeying a 'return back to HQ' order, as Locke was customarily sent to retrieve him. When the two finally do catch up, they have a brief 'perp tries to escape the law'-style kerfuffle, before reconciling their differences in pursuit of Cortana herself.
And... that's it. A good few year's worth of PR materials, viral marketing and buildup completely failing to pay off, with Guardians ending on a Halo 2-style cliffhanger that required you still look to the future for the really good stuff.