Remember when Facebook Inc. (NASDAQ:FB) wanted to buy Snapchat for $3 billion? Those days are long gone. Earlier this week, the social network took the wraps off of Slingshot, a short photo and video messaging service for Android and iOS.

Yet there's a catch. You can't just sign up and start receiving messages. To see what your friends "sling" your way, you'll first have to reply back with a photo or video of your own. Slingshot only works when you're willing to engage in back-and-forth digital conversation. Should investors like the approach?

Facebook introduced Slingshot earlier this week. Credit: Facebook.

Why this matters
I'm skeptical, but I'm also certain that Facebook had no choice but to build Slingshot and find a way to make it different. Snapchat is huge, and growing fast: users were sending 700 million photos and videos per day last month, up from 400 million photos a day in November and 60 million messages a day in February 2013, Business Insider reports. Just the sort of massive engagement Facebook paid up for when it acquired WhatsApp for $19 billion in February.

Now Slingshot will try to duplicate Snapchat's success by gamifying the sharing experience. Want to unlock that video a friend sent you? Send one back, and watch as your smartphone's screen becomes a sort-of scorecard that encourages you to unlock more messages. Back, forth, back, forth.

How Facebook monetizes this process isn't entirely clear at this point. All we know for sure is that Chief Executive Officer Mark Zuckerberg and his team want to lure us into using Facebook more on the theory that higher engagement will lead to better data, better ads, and more revenue. But don't take my word for it. Here's Zuckerberg's opening remark from last quarter's earnings call:

"We continue to grow our community in size and engagement, with nearly 1.28 billion people now using Facebook each month and almost 63% visiting daily. We also reached new milestones as a mobile company, with more than 1 billion monthly actives on mobile and almost 55% of our daily actives only connecting on mobile."

The message: We'll do what it takes to get our users spending more time with us. Building products like Slingshot are no doubt part of the strategy. Is it working? You tell us. Please leave a comment to let us know if you've tried Slingshot, and if so, what you think of it as a potential moneymaker for Facebook.