Each day, you get a new board with some pre-placed tiles. These tiles must be used on the board. Apart from that, you are completely free to place tiles and make words yourself.
Approved words earn points based on the letters they contain. Words that are not approved give negative points.
Play and improve your score until midnight. The player with the most points when the day ends wins that day's crossword. Points accumulate over time.
Under Results, you can view previous boards and scores. You can also go back and see boards placed by both yourself and other players on earlier days.