Mo Dao Zi Shi is based off of the novel of the same name by Mo Xiang Tong Xiu, and its honestly breathtaking. The art style and animation is the best of the best and some scenes will take your breath away! The characters are very well developed and the story just sucks you in. Wei Wuxian is a very enjoyable protagonist, and Lan Wangi is as well!
Season 1 has a total of 15 episodes, and Season 2, which aired in July of 2019, has 8. They are all legally available to watch on Youtube now! I do recommend that those who are interested in watching this series to read the novel first. It helps you understand the plot and characters a bunch. Unfortunately, since China does not like portraying LGBT relationships, the romance between Wei and Lan is extremely dulled down in the donghua. The novel, however, does not dull it down. Do not let that fact discourage you from watching the donghua! (anime) It clearly has its moments of romantic tension! Exiled Rebels Translations are the best at translating the novel and have translated the entire novel as of 2019 in English. Just look them up!
If you love fantasy, mystery, action, and history-inspired anime with a dash of subtle romance, then Mo Dao Zi Shi is definitely for you!