From the developer of GUNDEADLIGNE here's another shmup for the Wonderswan only available as an homebrew(you need the wsc development kit to play it).
But I founded a Windows Demo(emulating the original game I think) with no sound and with only keyboard support.....but very interesting
I think this is a nice game, considering it's a VERTICAL HANDHELD shmup!
here's a direct link to the file(lzh compressed)
Arial - Wind of Wizdoms (PC demo of a Wonderswan game,lzh compressed file)
http://www20.cds.ne.jp/~murasame/source/arial.lzh
Murasame Homepage
http://www20.cds.ne.jp/~murasame/