Details are light at the moment, but there's a trailer embedded below that should give you an idea of how deathmatch plays out. Spoiler: It looks like deathmatch! Not a slight against the game whatsoever, mind you, it's just hard to make the mode look particularly unique without betraying the elegant simplicity of running around and sticking a virtual shotgun in someone's face. Id has a Twitch stream scheduled for next week where it'll show off more of what's coming in the next free update.
Xbox is hosting the stream on its Twitch channel and fittingly enough, there will be a custom Doom;-themed Xbox One S up for grabs in addition to copies of the game signed by the development team. Want in? Then set a calendar reminder for next Tuesday the 13th at 1pm Eastern.