Worried about the complexity? Your game could just feature any form of block
creation/destruction as a primary mechanic, without including
a full voxel-worldbuilder!
Have an idea to make it more "gamey"? Feel free to add goals or challenges to your game's
world; it doesn't have to be a simple sandbox.
Keep things simple to stay on track, flip the concept on its
head entirely, or dig deep into optimising a
pocedurally-generated voxel landscape.
Just do whatever is going to help you grow as a game dev, and
maybe even finish a little game!