Flowers Are Bait - Chapter 59:

Six months ago, tens of thousands of black phantom towers appeared all over the world, floating above the cities. Chemists, physicists, religious people… all of them could do nothing.

Six months later, people became used to the towers and no longer paid them attention.

One day, Tang Mo saw a flying insect crash into it instead of going through it. The next day, a sharp and clear child-like voice issued an announcement to all humans.

“Ding dong! November 15th, 2017. The earth is online.”

The black tower’s three iron-clad rules:

1. Everything is explained by the black tower.

2. 6 o’clock to 18 o’clock is the game time.

3. All players, please strive to attack the tower.

- Description from Novelupdates

A decade ago, the first dungeon gates appeared, but some vanished before they were ever conquered. The MC, a low-rank hunter, awakens the Lost Gate System, granting him access to these forgotten dungeons where legendary monsters and artifacts are trapped. Each completed lost gate grants him absurd power, but also reveals terrifying truths—these dungeons are prisons for ancient beings who want revenge.

Betrayed and left for dead, Richard Blackwood—formerly known as the world renowned hero Astralis—awakens a decade later to find the world has moved on, and an imposter now wears his mantle. Disguised as a rookie in the Mage Guild, he quietly hunts for answers.'If my little sister is levelled above me, then what about everyone else? How much stronger have the bastards who betrayed me grown while I was dead?'Richard must grow stronger once again, and rise much higher than the S-Rank.'What the fuck? I almost die, and I get a power up?'Not harem.

When she woke up, Lake returned to the classroom of the third year. The classmates were in class with swords and sticks, and the teacher became a female Taoist.
The little fat man in the back seat, how to put two big hammers under his chair.
Rick found this to be a global era!

- Description from Uukanshu (translated)