For the first time in almost a decade, a new Halo sustains a healthy, active player base. Josh Holmes, 343 Industries studio head, says Halo 5: Guardians' player retention is the best since Halo 3. While each Halo iteration sells millions, both Halo: Reach and Halo 4 saw its player population nose dive a few months after launch. Halo 5 lives post launch because of the one characteristic many multiplayer games lack: skill gaps.
Developers roll out regular, sometimes free, content updates for their games, but content alone won't satisfy your player base. Halo 4 released regular map packs with free Spartan Ops missions every week. Raptr, a once console gameplay tracker, conducted a case study on Halo 4 and the hours logged during Spartan Ops releases. Despite the free missions each week, they failed to stop the plummeting playtime. In December, a month after launch, Halo 4's weekly playtime dropped from 400,000 hours to just below 168,000 by the end of January. While a drop-off makes sense post holidays, a month later it plummeted again to just above 110,000 hours. Regardless of the combination of free content and paid DLC, the total hours played dropped faster than in Halo: Reach.
Competitive games like DOTA 2, League of Legends and Counter Strike: Global Offensive, sees stability and even growth in their population because of competitive skill gaps. High skill ceiling games separate average players from the best players, but it also encourages practice. No one wants to get worse at a game, and so they return to - at the very least - perform to their ability. There's an addictive quality in competing, and an even greater feeling when competing at a high level.
Competition breeds player investment, yet it won't matter if the game lacks in quality. I don't attribute much to review scores or aggregate score websites like Metacritic, but they do mean something. Positive reviews for Halo 4 and Halo: Reach at least indicates a positive reception at launch. I can't quantify the quality of either game or even Halo 4's post launch content. All I can say is: I played most of Halo 4's DLC and I enjoyed it, but I didn't play between content releases. To keep players invested, games require both a combination of exciting content and challenging mechanics.