Creative gamers may like playing a lot of uniform, standard games, but there will come a point when they'd want to create a gaming world of their own, even without developer or programming skills. This is why sandbox games like Minecraft have massive popularity. What if you can have one that is a sandbox, platforme, puzzle game and is also a massive multiplayer world? This is what Cubic Castles is trying to be.
The developers of the game (who are mostly ex-Popcap Games employees) have found a way to combine the Minecraft-type of building and mining with the fun, virtual gaming world of the classic Nintendo platforming games. You can create whatever you want on the piece of land that you've claimed and then let other people in to play the game you've created.
You can also go and play in the mini RPG worlds that others have created. Basically, anything goes in this world (but with parameters of course to protect the players' own created games) and the customization options are massive. You can also personalize your playing character, making it as cute as possible (it is Nintendo-like after all). You can also build collaboratively with the other players, anything from puzzles to parkour runs to 3D platformer games. The game's world biomes have resources that you can mine in creating your game; from forests to mountain ranges to tropical islands and more.
Cubic Castles is free to download from the Google Play Store. There are some in-app purchases available, but only for some premium items and not to "buy to win." Everything else in this world can be "bought" with in-game currency or cubits, which you get when you're rewarded.