At the moment i'm postponing this project until i get some propper graphics. If your up for the job then post it in the public forum on this project then start making them. (you might want to have a look at the actual game first)
I don't think the graphics are a problem at all. I think the engine could use a little work, i see no reason to just aim in 8 directions. I have a 360 degree engine, and it also can do a good shotgun type blast, where it shoots 5 bullets in a arc shape sort of, and some other stuff.