Onslaught, the downloadable extension to Call of Duty: Ghosts, is free to PlayStation 4 and PS3 gamers until tomorrow afternoon.
The trial has been running all weekend; it lasts until tomorrow at 1 p.m. ET. Onslaught features four new maps plus "Nightfall," the first of the four-part Extinction campaign pitting players against an alien threat.
Activision ran a similar promotion for Xbox One and Xbox 360, which had the DLC on a timed-exclusive basis, back in March. Xbox owners already are on the second chapter of Extinction, "Mayday," released on April 3.