Observations:

• There are 15 players, however, the intro displays on screen that there are 16 survivors. It might be implied that Yasuhiro Hagakura is the 16th player, but he is not even present in the 2D sprite image.
• Edit: One of the very first death in Danganronpa was Mukuro Ikusaba posing as Junko Enoshima. The very first death in Danganronpa 2 was The Ultimate Impostor posing as Byakuga Byakuya Togami. It is a possibility that someone posing as Chisa Yukizome.
• All three of them were killed by a stabbing weapon.

ROUND 1:

• Daisaku Bandai witnessed violence by Juzo Sakakura. Poisoned by forbidden action.
• Attacker: Killed Great Gozu. Seemingly by a stab in the heart. In the games, the second death was by a bludgeoning weapon. Kirigiri was later seen taking off the mask and inspecting his head.

ROUND 2:

• Officially, that was the end of the first time limit, Kirigiri said it was the second one. Maybe she included the sleeping gas bomb, before anyone even had the bracelets.
• Kazuo Tengan knows who the attacker is. He might also know of other people's Forbidden Action.
• Monaca Towa, however, does not know who the attacker is and admitted having nothing to do with the game whatsoever. Which is weird, considering she should be able to observe how Chisa Yukizome was killed and how the bracelets were put on, since robots aren't affected by sleeping gas.
• Kazuo Tengan was cut by Kyosuke Munakata.
• Attacker: Seiko Kimura crucified and stabbed.

ROUND 3:

• Again, two time limits has been reached, Kirigiri said it was the third.
• Right after all the players woke up, it was implied that around this time Ruruka Ando killed Sonosuke Izayoi by feeding him candy and killing him through his forbidden action. It's implied that she took the knife from Seiko Kimura's body and stabbed him in the chest, to imitate attacker's killing style.
• However, his body did not turn purple like every other poisoned victims.
• Like the games, it appeared to be a double murder, but there were two different murderers this time.
• Monica Towa reveals here that she had nothing to do with the game and that one survivor from Danganronpa 1 is going to die . She officially drops out.
• Even though it's revealed the true Miaya Gekkogahara is dead and Monica Towa dropped out, the intro of the video still includes her as an 'alive' participant.
• Koichi Kizakura died by forbidden action, saving Kirigiri.

My thoughts and theories:

• 7 out of 15 ( 1) are dead. 8 ( 1) remains alive. If the anime follows the pattern of the games, 2 more participants will have to die. With one last hidden character left, like in the first game.
• If the 'sideways death theory' still holds, then Aoi Asahina might die by self sacrificing herself and Juzo Sakakura might be killed by the 'attacker' during the third time limit. Possibly a closed room death.
• I believe Monica Towa's confession, that she had nothing to do with the game and hadn't killed anyone during the game.
• While I think Kazuo Tengan is the 'traitor' and started the murder game, (maybe due to blackmail?), I do not think he is the 'attacker' and the one behind the murder game. Maybe Monica saw him set up the murder game, but knew he wasn't really the mastermind.
• It's highly possible that Monica Towa referred to Aoi Asahina or Kyoko Kirigiri, as the one that's possibly 'going to' die. There are too many variables to say with certainty that the people outside the building will die. I believe Asahina and Kirigiri are the only two candidates.
• There's a theory that Asahina is switched with Yukizome, I don't believe that. I believe that's the real Asahina. Especially after the ending credits, you see a clip where Asahina is carrying Naegi on her back again and running.
• Kirikiri mentioned one time that someone's forbidden action might be showing their forbidden action. It's actually a possibility that this is Ryota Miterai's forbidden action.
• Kyoko Kirigiri's forbidden action might have to do with her giving fully truthful statements about her deductions.