pcgamer on doom 4 (twitter):
  Doom will run on idTech 6, according to Stratton. Will support 1080p, 60 frames per second.
  Gameplay demo getting started. Tons of gray steel walls, flames, and a shotgun that is comically large.
  A key feature will be stunning enemies with a shot, then smashing their face with your boots. It's happened five
    times already.
  A new twist on finding the yellow keycard: year off a corpse's arm and use it to open a handprint scanner.
  Breaking: barrels just exploded. Repeat, we have exploding barrels.
  Doesn't look like health regenerates. Enemies drop health when you squish them.
  A demon just ripped the player's arms off and beat him to death with them. The room is breaking out into a standing
    ovation.
  An adorable custodial droid is trying to clean up all the blood. It is not succeeding.
  The player is now exploring a dank, Mars cave system. This looks like some of the atmospheric horror from Doom 3.
  The hand-to-hand kill moves are varied and fantastically gory. And here comes the chainsaw.
  There's a huge variety of enemies on display. Small demons swarming with giant bullet-sponges.

geoffkeighley on doom 4 (twitter):
  Doom is an origin game. Fast paced combat. Set outside of UAC research facility on Mars being invaded be forces of evil.
  Today's Doom reveal is focused on showcasing combat. New cyber demon concept art shown.
  Melee combat is a big part of the new Doom.
  Live demo about to begin of Doom #quakecon
  Doom is built on id tech 6, 1080p 60 fps. Single player demo today.
  Demo is now on. Inside UAC facility. Lots of particles and lava. Heavy Melee combat, ripping out body parts MK style.
  Forget key cards. Player just ripped arm off guard to scan his fingers on a hand scanner.
  Doom team now showing second level.
  Chainsaw acquired. New level of gore unlocked.

some anon on doom 4:
  Fast-paced combat against multiple enemies at once - Doom 3 this ain't.
  Set outside a massive UAC research facility on Mars as it's being invaded by the forces of Hell.
  Hellknights, cyberdemons, revenants, mancubii, and other classic monsters were spotted throughout the demo.
  Classic Doom weapons, including the fan-favorite double-barrell shotgun return. Plasma rifle, rocket launcher, and
    the good old chainsaw were also shown off.
  Go fast. "Doom is not about about taking cover" said executive producer Marty Stratton.
  Doom is powered by IdTech 6, and will be for PC, PS4, and Xbox One. They are "committed" to 1080P at 60
    frames-per-second.
  Wonderfully gory close range executions, including special ones for dropping down on enemies from above.
  Revenants now have jetpacks and can hover about while firing rockets at you.
  At least one weapon, the combat shotgun, has an alternate fire mode, which allows you to charge up and release
    multiple shells in rapid succession.
  Sprinting, double-jumping and mantling are all possible, making for very fluid motion during combat.
  Enemies can teleport in for old-school style ambushes
  Dying results in a crazy fatality scene depending on what killed you a la Dead Space. Revenants rip your arms off and
    punch straight through your combat helment.
  Old school mechanics. No reloading your clip, hold as many weapons as you want, health and ammo pick-ups etc. NO
    REGENERATING HEALTH.

the-goddamn-doomguy on doom 4:
  Quick rundown of what I saw. They gave us so much gameplay!
  - super shotgun
  - Guns didn’t need to be reloaded
  - Hyper-gory (oh my god was it gory) with super quick melee finishers that were quite goreious.
  - Movement speed was pretty damn fast.
  - Revenants have fucking jetpacks now. JETPACKS
  - Monster design was pretty goddamn sick. Loving the new imps (not like that you sick bastards.)
  - lighting and atmosphere a lot like Doom 64.
  - Almost no scripted bullshit.
  - Tons of enemies almost constantly.
  - Music sounded Quake 1ish. (Very industrial.)
  - Project lead guy who came on stage sounds like he really understands the fundementals of DOOM.

  All I can say is I was VERY pleased with what my eyes saw.

  we all lost it when the chainsaw came out. sweet jesus

  Oh, forgot to mention: double jump! i have space jump now!

  So worth the trip. Holy crap.

  One of the finishers has you place your hands in an imps mouth and rip its fucking head open.
    flow of combat.

  The finishers were some of the hypest shit ever. They were satisfying but also lightning fast so it doesnt ruin the
    was incredibly detailed and visceral.

  I don’t think I put enough emphasis on how gory it was. This might end up one of the goriest games of all time. It

  Some of them were like ridiculously awesome wrestling moves.

  The zombies look really cool. They were all grotesque and deformed.

  Saw one new enemy type. Some kind of zombie with a laser beam arm.

  A revenant ripped a zombie apart for no reason other than it was just pissed i guess.
    upon a scene with zombies and imps duking it out (before the player interrupts with a rocket launcher.)

  A hell knight looked like it turned on a imp after catching a fireball. There was one area where the player comes

  I think i actually saw a couple glimpses of some monster in-fighting.

  The gun sounds made me fucking cream


tl;dr REVENANTS WITH JETPACKS, brutal infighting, brutal everything else, the-goddamn-doomguy likes imps
also they cut the stream right before the preview so if you weren't there, tuff shit
there's probably no leaks either
because fuck you