UPDATE 21/06/2016 11.38pm: The Doom demo has been extended indefinitely, developer id Software has announced.
"Due to popular demand, we're extending the #DOOM Demo!" the developer said on Twitter.
"This was initially for E3 week only. But we figured, what the hell," id added.
ORIGINAL STORY 13/06/2016 4.33am: You can play the first level of the new Doom for free this week.
Bethesda said it's making the level available to download for free on PC, PlayStation 4 and Xbox One from 13th June. It is, essentially, a Doom demo.
Meanwhile, id Software said new SnapMap tools and Hell visual themes are due out as free updates.
New multiplayer modes, including Classic Deathmatch, capture the flag, and capture and hold, are also in the works.
Doom's first DLC pack, Unto the Evil, adds three new multiplayer maps, new equipment, a new weapon, and the Harvester, a new player-controlled demon. It's out in July.
You can also see what else Bethesda and other publishers announced at the show this year with our E3 schedule guide.