No. Nifty Island is free to play, although it is desktop only so you have to download a desktop client. No mobile version currently. You can connect an empty wallet to the website. Everyone gets a free island to build on, if you want to upgrade its size/number of models/number of games/customize weather/sea/sky, you have to spend "blooms" in game currency you can earn by playing games or completing daily quests. You don't have to spend blooms to play, and you don't have to spend money to earn blooms.

I like the general model. The creator tools are awesome, I have been having a lot of fun making cool model sets and releasing them as free claims and seeing what people make with them :)