Gigawing is indeed a splendid game. I've played it many times on my Dreamcast (along with the sequel - aptly named - Gigawing 2)
It's just sooo damn 'busy'. There is so much going on at one time I really do not recommend playing this game under the influence of any alcohol at all. Maybe after 6 bottles of lucozade and a packet of smarties though
You ever play Mars Matrix Steve? It is also a great game, slightly insane too.
The Dreamcast has some absolutley superb shooters so try em out everybody!