I'm really pleased you're making good progress with this. I mean, I knew it would work in principle, but there were bound to be some rough edges and you're doing a great job of figuring the system out. That's very strange... what about when you click? Do the changes occur where the mouse cursor is or where the brush is? At any rate I'm not sure why this would happen. Perhaps you can print out coordinates as the mouse moves to see what is going on? Actually, I didn't imagine ppeople would use the brush marker in game mode (although you are welcome to). I expected people would want their own game-specific marker - e.g. you could just add a sphere to the scene, have it follow the mouse, and apply changes wherever the sphere is. But of course the built in marker is nice because it also shows the falloff. Yes, but not with the magic sculpt function. You will need to look at the standard API and set the voxels individually. Look at the 'ClickToCarveTerrainVolume.cs' script for an example of this.