Give everything solid textures and add a jumping mechanic. Add trees and blocky mountains like in minecraft. make it procedurally generate terrain like minecraft, add a block breaking mechanic as well.
Great. But the game is laggy for me because I am on a low end device. Optimize the game so that it doesnt lag on low end devices. Like make it so that only visible faces of cubes are shown and the procedural generation generate when the player is walking toward a chunk and ungenerates when the player walks away from one.