This is fun to play with. I like how the trees change when you use 'alt'.
After making some forests I experimented with inserting my own images, and while it looks chaotic I think it could make some cool stuff using this.
Wasn't expecting anyone to use that somewhat hidden feature just yet. This sprite replacement option needs some work, but you can check the included sprites for how to structure your images so they can work as tree parts, if you want to try that.