This is a top down 2D arcade style game that is mimicking the Atari 2600 version very closely. I am big into black backgrounds (though I have been called out on this before) because I feel otherwise you will easily lose track of the ball as this is supposed to be a fast paced, frenetic experience.
So I think all I really need is maybe some styling for the bricks, shield and possibly the ball. Right now the bricks are 50x50 pixels, the shield is 100x25 and the ball is a circle of diameter 25 px. The target behind the wall could be a place where things might get more creative. Perhaps an animated character of some sort.
I am trying to keep the color scheme consistent with your arcade box. So a player and their quadrant is either blue, red, yellow or green. To that end, one thought I had was to give each color an "elemental" theme so maybe green could be some sort of Tree monster thingy and the bricks and shield have a green vine and brown twig intertwined pattern? Maybe blue is water. Red is fire. Yellow is ... uh ... something.
Anyway, that's what I have for now. I hope to show up tomorrow with just basic colored rectangles and a somewhat functional game.
Hey David what kinda art are you looking for? 2-D? Top-down, or side-scrolling? I might be able to sling some prototype assets your way (or you could use them in the final version if you want), depending on what the style you are going for is. If its supposed to be really close to Warlords look, check out the "Commando" game on ProgFrog... that might be a good starting point for terrain...