It’s no surprise that the ‘Halo’ franchise is one of the most popular gaming franchises of the modern times, and the series has single handedly made a big impact on the marketing of the Xbox 360. Now, it seems, Microsoft has numbers to back up its claim and, per reports, the flagship franchise has now crossed 50 million units of sales worldwide.

Apart from the sales figure, the company has also announced that players have spent more than 5 billion hours playing Halo on Xbox Live. Collectively, ‘Halo: Combat Evolved,’ ‘Halo 2,’ ‘Halo 3,’ ‘Halo 3: ODST,’ ‘Halo Wars,’ ‘Halo: Reach,’ ‘Halo: Combat Evolved Anniversary,’ and ‘Halo 4’ amount to eight games in the series, and eight games selling 50 million units seems like a pretty big deal for any company.

However, prior the worldwide launch of ‘Halo 4’ in Nov. 6, the ‘Halo’ series stood at 46 million in sales, which means that Microsoft's newest entry has sold nearly four million copies thus far. ‘Halo 4,’ as reported, has generated $220 million in 24-hour revenue at launch, with $300 million expected for its first week.

Bungie Studios, per a Gamespot report, “created the Halo series, though the company has since moved on to an all-new franchise to be published by Activision. Microsoft's new 343 Industries label is now responsible for all things Halo and is currently working on at least Halo 5 and Halo 6.”

This is a major development after it was reported back in October that since its launch in 2001, gamers had purchased more than 46 million Halo games, driving nearly $3 billion in revenue.

At the time, Microsoft went on to break down the launches of past entries in the franchise, stating first-day sales of Halo 2 hit $125 million, with Halo 3 notching $170 during its first day, and Halo: Reach besting that game with more than $200 million in sales during its first 24 hours. Of course, this was before the launch of the highly acclaimed ‘Halo 4.’

Additionally, Microsoft has also announced a new free-to-enter ‘Halo 4’ tournament. The ‘Halo 4 Infinity Challenge’ will go live on Dec. 17 and tasks players will compete on global leaderboards across the game's 'War Games' and 'Spartan Ops' modes for a chance to win prizes.

Players can register for the ‘Halo 4 Infinity Challenge’ via the promotion's Web site.