https://www.gamespot.com/articles/get-grand-theft-auto-5-on-pc-for-16-ps13/1100-6460699/

The PC game retailer Green Man Gaming is running a big Summer Sale right now, with particularly good deals appearing and vanishing daily. The current Deal of the Day puts Grand Theft Auto V in the spotlight, bringing the price down to $16 / £13--the lowest it's ever been. But you'll have to hurry, as the deal only lasts until July 25.

The reason for the discount is to celebrate the "After Hours" update that just hit GTA Online. After Hours introduces a bunch of things related to nightclubs to the online portion of the game. You can buy nightclub properties, deck them out with the decor of your choice, hire DJs and support staff, and host parties. Your nightclub can also act as the central hub for your criminal enterprises.