The short teaser for The Last of Us Part 2 leaves its story open to interpretation, but some fans think they've already cracked the game's biggest mystery.

After a lot of speculation over whether a sequel would be made at all, The Last of Us Part 2 was officially announced at PSX last weekend with a short, but emotionally-charged teaser trailer. There wasn't a lot to go on, in terms of how the story will play out, but that hasn't stopped eager The Last of Us fans from trying to figure it out anyway.

The trailer features Ellie, who has been confirmed as the main character, strumming a sad song on a guitar she finds in the bedroom of a derelict home shortly after scuffle with the previous occupants. As she struggles to control her shaking hands to tune her guitar, blood from a fresh wound streams down the side of her head. She begins playing and singing as Joel walks through the house riddled with corpses until he finds Ellie, who swears vengeance on an unknown party.

What's of particular note, and is the backbone of this theory, is that Joel is only seen and heard from behind. His face is never shown. According to VG247, this has lead fans to believe that The Last of Us Part 2 is pulling a Sixth Sense. They predict Joel will likely be dead at the time the story begins and Ellie is just interacting with him as some kind of coping mechanism or hallucination. Taking the ending of the first game into account, they suspect the Fireflies had a hand in Joel's demise and Ellie is seeking her revenge.

The theory has been trending on Reddit since the idea was batted around, and on Twitter as well (Polygon).

Plot twist: Joel is dead the whole way through TLOU2 and Ellie is imagining him while she hunts down his killers

— Marianne Craven ❄? (@miss_mariii) December 4, 2016

What if Joel is dead and Ellie is hallucinating. In act of revenge, Ellie is gonna kill the rest of the fireflies.

— Alpha ライアン (@AlphaFoxWarfare) December 4, 2016

But not all fans are on board with this theory. There are many other alternate theories on Reddit and plenty of people who believe Naughty Dog would never go with such a cliché plot twist. Some folks on Twitter aren't buying it either.

Why does everyone assume Joel is dead? This rumor has blown up so much I have ppl arguing it's straight up fact. >.<

— Kathleen (@Kathleenmms321) December 5, 2016

All anyone knows for sure is that both Troy Baker (Joel) and Ashley Johnson (Ellie) are confirmed to return for the sequel and the game's creative director Neil Druckmann has confirmed the story is about hatred, a theme that was pretty evident in the trailer. Druckmann also took a moment at PSX to discuss the reasons for bringing back the two original characters, a decision that has concerned some fans who believe a sequel will undermine the original's poignant ending.

Considering how critically beloved The Last of Us was, developer Naughty Dog is likely making sure the sequel isn't more of the same. The co-director of the original game will not be returning and a writer from Westworld is joining the creative staff, which should change some things up.

Outside of these small details, and whatever can be gleaned from the teaser, the story in The Last of Us Part 2 is a mystery until more details surface. Without even an estimated release date, fans shouldn't expect to know more for a while. They will just have to rely on theories and speculation until then.

There is currently no confirmed release date for The Last of Us Part 2.