Cool idea! I think there were some problems with the breaking textures, but the gameplay is there. If you want to go further with the idea, I have some suggestions:
- Whenever you click on a block, add a voxel hand with an animation as if hitting the block from a 1st person view. You can achieve this with a SubViewportContainer/SubViewport combo with the model as a child.
- When a block is broken, make it drop in pieces, can be made with particle effects.
- A chime on a chance to break a block with a "critical" hit in less clicks