I think a better Sprites and sounds would be better!
The Idea its very cool.
Keep practicing more and more little projects and system that soon you will create Better Games.
Keep training Art too.
Always focus on Excelence.
1% Idea, 99% Execution.
Study AI, Cenario Design and etc.
Beggin with simple and small projects.
<img src="smileys/smiley1.gif" border="0" align="middle" />