From Board Game Geek:
The new moon is a symbol for a new beginning, the perfect time to start something new and to plan your future — and that is what Nova Luna (lat. for new moon) is all about. In each round of this abstract tile-laying game, you have to plan your future anew, developing a new strategy to cope with what the moon wheel has to offer you.
On each turn, you have to decide which new tile from the moon wheel to place in front of you. Every new tile brings a new task you have to fulfill. In order to do so, you need to place tiles of the correct color adjacent to the task you want to complete, but these of course again bring you new tasks. Each time a task is solved, you may place one of your markers on it. So decide wisely and be the first one to place all your markers.