There is an achievement in BitLife where you ruled as a monarch for over 100 years. It's called Reign Over Us, and it's probably a much more difficult and complicated achievement than many might initially believe. Becoming a monarch is not too difficult, as long as you are an unmarried child. Probably the hardest part is putting up with it for 100 years as the main character. You have to assume the throne quickly enough to survive all the time.
The first thing you want to do is make sure your character is born into royalty. This is the fastest and most efficient way to ensure completion as quickly as possible. There are only a certain number of countries that allow royalties, so make sure your character starts in one of them. If they are not royal when they are born, create a new life and try again. Once you are born into a royal family, now the heat is on to claim the throne.
You must, however, be the head of the monarchy. You can be part of a royal family and be one of the lower ranking officials, with your older brother or your father as the king. When you inherit the role of king or queen, this is when the clock really starts for success. The best way to do this is to be born into the royal family, hope your father dies early so that you as a young child can become the king or queen early on. Alternatively, you can attempt to have your family members killed to assume the throne at the age of 14, but there are many risks involved.
Success, however, is a matter of luck. You can start a new life at an early age, because going through 100 years, in territory 105 and 110 is quite difficult. You had better inherit the title of king or queen before you are 10 years old.
