When investors think Microsoft Corp. (MSFT - Get Report) , they often think cloud computing, operating systems and web browsing.

But the Action Alerts PLUS holding is hoarding one secret weapon that's kept a loyal audience for years: the Xbox.

On Wednesday, Microsoft added three new games to its Xbox One backwards compatibility catalog of older games that can now be played on current generation consoles. Microsoft first started releasing Xbox One backwards compatibility titles in October 2017, and is set to release the next batch this spring, according to Gamespot.

So just how important is the Xbox to Microsoft?

The company tallied $96.7 billion in revenue in the fiscal year ended June 30, 2017, up 5% from a year earlier. Of that, about $9.26 billion came from Xbox sales, according to filings with the Securities and Exchange Commission.

Wall Street forecasts total Microsoft revenue will grow to $107.2 billion in the fiscal year ending this June. So how big of an impact could a showstopper like the Xbox One and its family of gaming consoles have on Microsoft's top line?

In 2017, Xbox hardware sales slipped 21% from a year earlier, due mostly to lower prices for consoles and a decrease in sales volumes. But overall gaming revenue was bolstered some by software and services sales, which grew 11% in 2017 as a result of more in-console transactions and an uptick in the revenue that came from those transactions.

But that was what appears to have been an off year with relatively few launches.

Here's the kicker: The highly anticipated Xbox One X wasn't announced until June 2017, only a few weeks before the fiscal year ended for Microsoft.

But in its most recent quarterly report for the three months ended Dec. 30, 2017, Microsoft reported an 8% increase in gaming revenue driven by Xbox One X hardware sales growth following the launch. For the quarter, hardware revenue increased 14% and software and services revenue grew 4%.

With even more sales time under its belt and more games available for a wider range of consoles, Microsoft could tee up further gaming revenue to bolster an anticipated 11% year-over-year sales growth.

TheStreet's founder Jim Cramer is bullish on Microsoft. Watch below to find out why.