The Lonely Hacker is an Android game that normally sells for $2.99, and right now Google Play is handing it out at no charge. No deadline has been stated for the promotion, which means it could revert to full price at any point, so it's worth grabbing sooner rather than later.
It's a straightforward pick for mobile players who like adding paid titles to their collection without paying for them, and for anyone after a self-contained game to keep on a phone or tablet.
Because this is a normal Google Play acquisition rather than a trial, the game is tied to your account once you claim it. You can uninstall and reinstall it later, on this device or another, even after the price returns to $2.99.