It's Jungle, Jungles often have thick grass where there is no tree cover.
The size is all in the textures, if I could import the older models I could optimize the texture sizes and format, but alas all I can do for quality is make them bigger.
Actually my tileset performs extremely well and has very low triangle counts, the only thing I'd be worried about is VRAM, I have no idea how much it uses.. It's probably not much though.
If you guys want I could come back to this and produce a 2.0 sometime and patch every little thing up, and optimize stuff more, add more animations and such. Also in a 2.0 I could put different ground textures in, depending on what you guys like!
Are you experiencing low framerates? If so, what are your system specs?
Edit: Oh yea and shadows are controlled in the options menu, my tileset doesn't add anything new to the engine. It works just the same as every other tileset. The graphics are 100% art department.