(taken from English Wikipedia entry)
Psyvariar 2: The Will to Fabricate is the sequel to Psyvariar Medium Unit and Psyvariar Revision, both of which were released on Taito's G-Net Hardware, and ported to the PlayStation 2 console. Psyvariar 2 was released on Sega NAOMI arcade hardware, and was ported for home release on the Dreamcast, Xbox, and PlayStation 2 consoles.
The Psyvariar series of vertically scrolling shoot 'em ups requires the player to risk all in order to get high scores. Your ship is largely invincible, apart from an area a few pixels large in its center. Points are gained not only from destroying enemies, but also from "buzzing" enemy bullets - scraping them with the invincible sections of your craft.
When leveling up, the player is given a brief window of invulnerability, allowing the player to risk possible death in trying to "buzz" more bullets to continue the "level up" chain. It is this "risk/reward" structure that defines Psyvariar 2's unique brand of gameplay. Unlike the PS2 and Xbox versions of the game the Dreamcast version has no extras or an auto buzz function. It was the first version released and is the most stripped down. Nevertheless, it is considered the most valuable and is quite sought after in second-hand markets.
Official Website: http://www.success-corp.co.jp/software/ac/psyvariar2/index.html
Review (in English): http://shmups.classicgaming.gamespy.com/reviews/psyvariar2/index.html