Following other publishers such as EA and Ubisoft, Rockstar Games is rolling out a games launcher for Windows PC. It'll pull your Rockstar titles together in one place, including those you've bought through other stores such as Steam (though it doesn't support some games).
Among the features available in the Rockstar Games Launcher are cloud save support for various titles, automatic updates for games and news updates from the publisher. Naturally, you can buy games there too.
For a limited time, those who install the launcher can claim a free copy of Grand Theft Auto: San Andreas. Looking ahead, the rollout of the launcher is potentially a prelude to Red Dead Redemption 2 coming to PC.