Higher and higherG 25

Higher and higher G25:
Level up a dweller from Level 1 to 25

An achievement that you should not worry about, as you will spend a lot of time playing this game, at one time or another this achievement will be unlocked, this achievement consists of level up a dweller to level 25, you can do this by pressing in the room where the dweller is, it will have a green arrow over the head, it increases if he/she are working with something or training.