Shikigami no Shiro = 式神の城 = 式(shiki) 神(kami) の(no) 城(shiro)
"Shiro" here means "castle". "Shikigami" does not appear in my dictionary, but the individual characters themselves translate to "[ritual][god/soul]", so it probably means "divine ritual". Or it's probably a proper noun.
The game itself is a rich title featuring multiple characters posessing very different attacks, and hence very (very very) different playstyles. If you fly very close to bullets, your shots will be of a powered up version.
Shikigami no Shiro 2 has been released to the North American world under the awfully awful title, "Mobile Light Force 2". If you want the game in its unadulterated format, best get the Japanese version.
In Psyvariar 2, levelling up by buzzing gives you momentary invincibility. Furthermore, selecting the Buzz Type mecha enables a player to defeat enemies without ever firing. There are superplay videos on the web; be sure to view them if you're interested.
So there... today's useless trivia.