Mercenary God: Reborn with a talent for fighting. - Chapter 38: Ch Alex vs Selena.

Born of a great family, world shaking genius.

The bad news, at least for me, is that I died. The good news is that I was reincarnated into someone else's body who lives in a cult full of beautiful women... but this cult forbids love. Well, one can't have all the good things. I thought I was safe until the worst happened. A system appeared that told me that I would die if a girl didn't accept my confession within a month... I have to get out of that cult now.Every 10 days I upload 15 chapters at once on Patreon.

The aliens came with hostility.
Facing the invasion of aliens, human beings are weak like ants.
So this is the end, the real end.
But there is resistance when there is an invasion.
For some, this is not the end, it is war.
So this is war.
Real war!

- Description from Qidian

One day, Luo Jian woke up from his sleep and found himself in a locked chamber where the door and window were all sealed. A note with a few lines written on it was tacked to the wall: “Escape from this room within an hour, otherwise, you will die.”

There is a sequel called Reincarnation Night (轮回之夜) that takes place in the same universe but has different main characters

- Description from Novelupdates