It has potential
Quite fun, and the upgrading element is satisfying if somewhat tedious. The starting score function is also a good idea, rewarding you for rushing through the waves. The music was vastly inappropriate and repetitive though, and gameplay was at times frustrating. As for graphics, a lot more effort is required; everything looks shoddy and flat. Some of the upgrades are just silly, and none of them make you say "Wow, that looks cool." An improvement in that area would give the game a much better feel.