Okay, first you need to make them look darker. Because tunnels are underground. The only lightsources you have is light from candles and stuff. A hole in the roof would also be a possible light source. And how's there supposed to be snow inside a tunnel? I suggest you use dirt tiles instead. Also I think it would look better with more doodads like crates and stuff. The first picture doesn't look bad. But I think the rocks in the second picture look wierd, and there are some holes.