A free weekend has commenced for Saints Row IV on Steam as the open world action sequel is gratis to play between now and 4:00 pm EST Sunday, with a 50% discount available to those who decide they want to buy it. Here's word from Steam News:

The US President must save the Earth from alien overlord Zinyak using an arsenal of superpowers and strange weapons in the wildest open world game ever.

The epic conclusion to the game that changed all the rules! The Saints have gone from the crackhouse to the White House—but the Earth has been invaded and it’s up to you to free the world from Overlord Zinyak and his alien empire. With homies new and old by your side, and an arsenal of superpowers and strange weapons, you must save the world in the wildest open world game ever!