someone knows what this is about and if it has a normal duration or just 10 m?
It is a short drama.
Here is synopsis from Tencent:
In the previous life, the sisters Manzhu and Shahua were known as the twin sisters of the gods. During the calamity, Manzhu suffered a backlash. Shahua saved Manzhu and suffered a disaster. Manzhu ignored the pain of the backlash and went to rescue Shahua. Shahua could not see her sister. Suffering, they decided to sacrifice themselves. The gods were moved by the love between the two sisters and decided to give them a chance to meet when the flowers on the other side bloomed, but they agreed to "not recognize each other" before meeting. Manzhu waited and waited, and finally saw Shahua, who had lost his memory, in the human world. But at this time, Shahua was already a mortal named Qianxia, and she was the chief arrester of the Jingxie Department. And just after Manzhu appeared, a legend spread in the prosperous Guangling City. There was a place in the city called Huanjing Pavilion. Its owner was a mysterious woman in red. According to legend, as long as you have a wish to come true, she will make it happen. I can help you realize your wish, and the price of realizing your wish is to exchange your "thought" with her. Qian Xia was also involved in the investigation of the murder case, and started an investigation journey with the beautiful proprietress Manzhu.
Anyone who has finished this drama, could you please tell me... does this series has a similarity to I've Fallen…
I watched I've Fallen for You so long ago that I don't quite remember the storyline, but I don't think it is similar to this drama. This one is set in a game, FL and ML (NPC) didn't know each other before (not childhood friends). They grew feelings during their investigations.
Do you know why ML killed her family?? ML loves her?
FL's family was convicted of treason, so the whole family must be exterminate. ML loved her, that's why he married her before killing her family. When she married into his family, she no longer belonged to her natal family, so that she didn't have to be killed.
2 
Here is synopsis from Tencent:
In the previous life, the sisters Manzhu and Shahua were known as the twin sisters of the gods. During the calamity, Manzhu suffered a backlash. Shahua saved Manzhu and suffered a disaster. Manzhu ignored the pain of the backlash and went to rescue Shahua. Shahua could not see her sister. Suffering, they decided to sacrifice themselves. The gods were moved by the love between the two sisters and decided to give them a chance to meet when the flowers on the other side bloomed, but they agreed to "not recognize each other" before meeting. Manzhu waited and waited, and finally saw Shahua, who had lost his memory, in the human world. But at this time, Shahua was already a mortal named Qianxia, and she was the chief arrester of the Jingxie Department. And just after Manzhu appeared, a legend spread in the prosperous Guangling City. There was a place in the city called Huanjing Pavilion. Its owner was a mysterious woman in red. According to legend, as long as you have a wish to come true, she will make it happen. I can help you realize your wish, and the price of realizing your wish is to exchange your "thought" with her. Qian Xia was also involved in the investigation of the murder case, and started an investigation journey with the beautiful proprietress Manzhu.
https://ko-fi.com/Post/Eng-Sub-FULL-VERSION-Fei-Chai-Xiao-Wu-Zuo-%E5%BA%9F%E6%9F%B4%E5%B0%8F-C0C3RYRA9
https://ko-fi.com/i/IM4M5S3TRJ