YouTube: 'Call of Duty: Black Ops III' was 2015's biggest game

The "Call of Duty: Black Ops III" reveal trailer tallied 21m views between April and December 2015.

This year's addition to the annual Call of Duty franchise was the top release according to YouTube's metrics, with sports title "FIFA 16," animatronic horror "Five Nights at Freddy's 3," dino-taming sandbox "ARK: Survival Evolved" and petri dish sim "Agar.io" also doing well.

YouTube's Top Ten Games of 2015
1. Call of Duty: Black Ops III
2. FIFA 16
3. Five Nights at Freddy's 3
4. ARK: Survival Evolved
5. Agar.io
6. Five Nights at Freddy's 4
7. Fallout 4
8. Mortal Kombat X
9. Batman: Arkham Knight
10. Until Dawn

Facing down accusations of staleness and stagnation, "Call of Duty: Black Ops III" benefited from a three-year development cycle (instead of the usual two), emphasized the sheer breadth of content that the solo campaign and multiplayer arenas offered, and leaves 2015 as YouTube's top game.

Second place is reserved for the top ten's only sports entry, soccer game "FIFA 16," which racked up a combined 34 million views between a Play Beautiful advert featuring Argentina's Lionel Messi and Sergio Aguero, the mid-year trailer presented by Pelé, and an introduction for the "FIFA 16" cohort of women's teams.

There were two entries for the "Five Nights at Freddy's" franchise, corresponding to the third and fourth games' March and July releases respectively, crowning a year of fame for developer Scott Cawthon who launched the series in August 2014.

Low-fi and initially browser-based, cell growth and expansion game "Agar.io" proved a worldwide hit, lending itself well to videos lasting 10 minutes or less, with multi-million view clips uploaded by hosts such as Bulgaria's Bodil40, Chile's JuegaGerman, the El Salvadorian Fernanfloo, and high-level Agari.io specialist Wun Wun.

With official trailers and clips for "Fallout 4" and "Batman: Arkham Knight" dominating the most popular video rankings for each game, "Mortal Kombat X" offered some variation on the formula as new videos from Conan O'Brien's Clueless Gamer segment, Russian YouTuber EeOneGuy, Australian video team RackaRacka accrued over 10 million views apiece.

Similarly, PewDiePie led his viewers on a 10-part jump-scare journey through horror game "Until Dawn," with French speaker Squeezie and Spanish-language JuegaGerman also picking up sizable followings for their own playthroughs.