Although 2015 brought gamers some pretty big titles, the most popular, at least on Twitter, is still Grand Theft Auto V, a game released several years ago.

The 2013 game topped the social media site as the most-discussed game of last year, with a grand total of 30 million tweets.

Coming in at a close second, according to Twitter Gaming, was Call of Duty: Black Ops III with 25.5 million tweets, which isn't a bad showing considering that the game released late in the year. FIFA 16 came in third, with 7.1 million tweets.

Fallout 4, one of the most-anticipated games of the year, only managed 5.4 million tweets, but it also got a late start last year, thanks to its release in November.

So why is a game from 2013 still the most-discussed title on Twitter? Part of its popularity probably has something to do with its availability: not only is it playable on the newer consoles, but it originally released for the PlayStation 3 and Xbox 360. Considering many gamers still haven't upgraded to new systems, that probably helps drive some sales. Its re-release on the PlayStation 4 and Xbox One, though, also went over well, with critics and fans alike.

Grand Theft Auto V also has an active community of fans as well as modders who continue to develop mods for the game.

However, it's the online mode of the game that probably drives the most sales and discussion. At the end of 2015, GTA Online had around 8 million players per week. Grand Theft Auto V publisher Take-Two Interactive also reported that its revenue rose last year by 169 percent from the previous year. Players stay engaged with the game because of the continuous stream of new content coming from the developer, as well as ongoing in-game events.

It's hard to compete with those kinds of numbers, so it makes sense that such a popular game would also rank highly on social media.

Other games making the top 10 tweeted list include Assassin's Creed: Syndicate, The Witcher 3: Wild Hunt, Batman: Arkham Knight, Star Wars Battlefront and Battlefield Hardline.