It started in a museum or art gallery something like that, there were exhibits everywhere, but there was also a rail at the ceiling that you could ride around on, kind of like in Bioshock Infinite. There were also multiple floors, I was on the ground floor and I decided to go up stair to the first floor, on the stairs was sitting my elementary school classmate, I didn't really have anything to talk with him about so to avoid an awkward conversation I stepped away though a door and the door led to a theme park that was really big and had different attractions.
I went to one at random and it was like a thing where you walk on a path and there are people acting as Star Ward characters and they interact with you, like LARP, but I'm not a Star Wars fan, they were clearly making some Star Wars references I was not able to catch so it made it awkward so I decided to step away again, I went down a water slide and at the end instead of going down the designated path I went down some stairs into a basement area that was clearly not for visitors of the theme park.
There were some people there acting as alien monsters there, for the theme park, but then out of nowhere real alien monsters (that looked the exact same as the face actor alien monsters) appeared out of nowhere and they just started killing people. I started running away. Along the way I somehow just knew that this wasn't only an invasion of the theme park, it was an invasion of all of Earth, there was panic everywhere and everyone was trying to escape too.
As we were trying to find a way out we made our way underground into some massive sci-fi megastructure secret scientist research base. It was really big and we just kept running, along the way we kept losing people until only a very small group of us remained. Eventually we made it to a strange room that was like a survival bunker with supplies and a bathroom and kitchen and bedroom and stuff, but also it was like a hangar overlooking a very large space in the megastructure.
It also had these weird rocket things, that were basically kamikaze-nuke-rockets, we knew that people have to get it (one per rocket) and fly with them and then nuke the aliens which is the only way to defeat them, but of course you will die in the process (don't ask how this doesn't wipe out the rest of humanity in the process, in dream logic it just works).
Another important detail the walls aren't just walls, they're like terrariums or aquariums for animals, like a glass box basically, except all of them have extremely deformed dead mutated humans.
I think to myself that I don't want to get into the kamikaze-nuke and die so I just want to stay back in the room and survive (there were fewer nukes than people in our group), but then I notice that some other people in the group start mutating, turning into the deformed people like in the glass boxes, I realize that there is radiation in the room which is rapidly mutating all of us.
It seems like a fate worse than normal death so I decide I want to die quickly so I jump out of the hangar door into the empty space of the megastructure, as I jump there suddently is no gravity, so I fly for a while (the megastucture is really really big), but eventually I reach a floor on the opposite side and it has a proximity mine, the mine detects me even before I git the floor and it explodes, killing me, which wakes me up.