Question: What was earth like before the start of the game, was it more advanced then today or closer to current time.
Before the start of the Ascension Program, the world has formed into Federation. The technology was little lagging, as after the establishment of Federation; the World was facing countless cultural challenges.
Not related to the question but Federation was only possible because of the interference of Mages. Then again mages were also the ones behind the first and second World War.
Question: You said that kai could choose between a plethora of gifts ranging from f rank to s rank but there should be a gift better than ki control in this aspect should it not there could have been an b rank or a a rank gif that should have relatively easier constraints and proportionally easier acquisition conditions and what are the rules for the choice of gifts as it seems that one can only choose d rank gifts or below when undergoing the third heavenly tribulation.
There are definitely better Gifts that could help Kai with his current situation. However, as the ranks of gift goes up, the price of materials needed for the sacrifice along with the difficult of the Heavenly Trial increases. In early chapters, there was small talk about a character failing his Heavenly Trial.
If one want one can full all his 9 slots with S-rank gifts. In fact it is a main theme of one of the main story in Ascension Program.