I created my own system - Chapter 275 Festival?

“Margaret, you’re the older sister, you have to give in to the younger one.” Because she had been born a few seconds before Elizabeth, those words clung like a curse to Margaret for the first 18 years of her life. Whether it was her beloved teddy bear, pretty dresses, Halloween candies, or parental love, if Elizabeth asked, she had to unconditionally yield them all up to her. Since young, Elizabeth had weighed down on Margaret like an enormous mountain and suffocated her. Fortunately she still had a boyfriend who had loved her for six years—Amster, the pack’s alpha. “You will be my wife and the future luna of the pack,” Amster promised.

Six years of companionship and Amster’s words had excited Margaret, who was turning 18 years old. She was going to welcome a whole new life today, but fate had played an enormous joke on her—Amster’s lover and fated mate turned out to be her twin sister Elizabeth! Margaret watched as Amster, who had said he loved her a second ago, exchanged a French kiss with Elizabeth in the next. Moreover, he also announced that Elizabeth as the luna. The only emotional sustenance Margaret possessed crumbled; once again what belonged to her had been snatched away by Elizabeth. What made things worse was when Amster begged Margaret to help Elizabeth entertain Wolf King Donald! All because Elizabeth knew nothing except how to wheedle and dress herself up.

Unable to refuse the request of her former lover, Margaret agreed to this. The gears of destiny began slowly turning at this moment. At the feast where Wolf King arrived, having worked hard without washing up for three days now, Margaret smelled an enticing scent. Betty, her wolf, was calling out happily for her mate. This was the smell of her mate! “My name is Donald, and I’m the king of werewolves!” Donald?! Wolf King! Margaret gaped. Her mate was actually the most powerful werewolf among them all! Margaret realized that her mate didn’t recall her s*xy and seductive younger sister. He only had eyes for her. She felt that she could believe in love again!

Fate, a gatekeeper who had been working for the castle, is beset by a few burdens.

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

A mecha otaku is reincarnated into another world as Ernesti Echevalier (Eru). In this world there exist huge humanoid weapons known as Silhouette Knight. Dreaming of piloting those robots, Eru, with childhood friends, Archid Walter and Adeltrud Walter: together they will aim to become a Knight Runner, pilot of Silhoutte Knight.