Let me sum it up

1. interdimensional creatures called keepers essentially keep the universe in order

2. some keepers were turned into bad alien things called apothicons

3. group 935 finds ancient material which is 115 (fabric of universe)

4. group 935 messes up, creates teleporter, dude teleports daughter to group 935's lab on the moon, girl steps into ancient machine on moon, rules all zombies

5. zombies are outcome of element 115 (fabric of universe-ish thing)

6. 4 heroes try to save the world from zombies

7. 1 of those heroes does experiments on other 3, brainwashing them

8. that 1 dude, german guy, richtofen, messes up and gets the entire world nuked by angering the girl in the machine ruling zombies.

9. german dude is cursed to (what is essentially hell), gets revenge on the girl's father

10. 4 other dudes in another universe, basically immortal to zombie infections, replicas of the other 4 dudes in other universe, shows up to save themselves and create a perfect, safe universe, lead by the other universe version of the girls father, and now he's good, helps the new 4 people

11. they get summoning key, the orb that the old man in the trailer (father of girl, aka maxis), have to kill off OTHER universe versions of themselves to preserve and keep their souls safe in that house you see in the start of the trailer (souls turn into kids)

12. maxis is tricked into touching orb by apothicon overlord, apothicon overlord steals his body, turns into that weird bearded floaty dude and he destroys the 'perfect universe' that the new 4 people created.

and t hats all it folks, i can go much deeper but... y'know