Fallout Shelter was announced at E3 by Bethesda as a quick little mobile app game for iOS, supposedly made to build some hype up for Fallout 4 (as if there wasn’t enough already) and tide people over til then. It was a free-to-play shelter building game that became very popular very quickly.

Now it’s been announced that despite letting you play as much as you’d like for free and only having real money purchases in the form of ‘lunchboxes’ that contained in-game items to add to your total stock of supplies the game has made $5.1 million in its first 2 weeks on market. Not bad for a little game not meant to make a profit according to the developers of the game.

While Fallout Shelter is currently an iOS-only game, an Android version is currently in development and should be out soon say Bethesda.