For me it’s about exploring new realms, and discovering new spirits and doing missions given by said spirits. Collecting items such as clothes and accessories is fun as well. I guess it’s not as intense as other games, but I like that you can do stuff your own pace - there’s no pressure or stress, just lots of beautiful visuals and wonderful soundtrack. Befriending fellow players and doing missions together is a plus as well.
There are purchases within the app - such as buying more candles (the game currency), or a “Season Pass” that gives you exclusive stuff whenever a new season in the game begins. You absolutely don’t need to pay for anything to enjoy the game, there are no limitations as far as in-game interactions go.