Skillz is a company that provides real-money components (gambling, iirc) for mobile games. If you have a mobile game, it's a platform you can tack on to allow your players to compete against eachother for cash (and so monetize your game).
That's the "buy an energy refill to chop more wood!" sort of games.
Now imagine if you pretend it's a competition. You can "beat the machine", as these games are dressed up. And you can wager on them.
Every casino in Vegas has lifers burning their cash. Now you spread that to over a billion devices with no gambling commission.
This is from their IPO S-1:
"We collect over 300 data points during each gameplay session to feed our big data assets which augment all elements of our platform. Our key data science technologies drive our player rating and matching, anti-cheat and anti-fraud, and user experience personalization engine."