You mean shmups (shoot'em up games)?
Try Cho Ren Sha 68K, it has got all that shmups fans could love - fast paced action, great enemies and powerup system, and of course lots of bullets in thd air (and it's free).
http://www2.tky.3web.ne.jp/~yosshin/my_works/download.html
Raptor: Call of the...