 Please review my DropZap web demo.  It's written using GWT.
blasdel: You absolutely need at least one carefully expository level to demonstrate the game mechanics. Play Wario's Woods for the NES, and you'll know what to do. Your textual description is awful, but I'm not sure how you could do it better -- so ditch it! Show, don't tell. Tell them just enough to inspire them to try it.Graphics. You don't need 3D anything, you don't need to turn the blocks into animal species with a story. You just need it to feel like someone considered it more rather than doing what the tools made easy -- taking stuff out will go a long way.You need sound effects, if not music.