Tower defense game Graphically boring

Hey, I am working on a little tower defense game, and even though its still far from being done, but it has come to me that it just looks very bad. I am not graphic desginer/builder/modeler, and I am really having trouble with idea to make the level environment look more interesting. And its not just the environment, but also the GUI and effects. Maybe I’m just criticizing too much since I am trying to make it as good as possible, but I am very convinced that it is just bad.
Here is some latest footage:

I will really appreciate ANY feedback, suggestions or ideas.

Well first of all, the map is just white and grey blocks. The bar above a troop’s head could use a UICorner, so could most of the GUI. The NPC’s are just grey parts, they need to look real, like the soldiers.

2 Likes