I don't think I will be spending a lot of my time on this one but it's fun. The blocks are adorable and give very nice "feel" to the building process.
Few tips:
- Construct button seems useless. Remove it and leave block select instead. Or make construct button take function from block select and remove "block select button".
- highlight on red block i am about to remove while I am in remove mode
- Sometimes I build in wrong plane even if I look at white ray. White ray is awesome but maybe additional one in X-o-Y axis could solve a problem.
- It would be nice, in some cases, to give all block already built *50% transparency to make building easier
- Make keyboard shortcuts list in author comments.