Purevex (lost PC space shooter game; 1997)
Purevex (ピュアベックス) by Nec is a 1997 Windows 95 3D vertical shoot 'em up. It's one of (if not) the rarest japanese only exclusive made for PowerVR pc graphic card chipset, it uses proprietary direct API called "PowerSGL", so it cannot be played with all cards.
Game engine and gameplay remind very much of Xevious 3D/G with some elements of Gradius.
Pieces of information and images about the game are very scarce. Only a few niche-forum activists claim to own a copy of the full CD-ROM and some YouTube videos showing the full version appear and disappear sometimes. A major chunk of information you can find is from its defunct homepage and this review, taken from (now dead) website 3dgaming.
Some shopping sites like Suruga-ya and Medio.bz have a page for the game, including front box scan, game price, release date and product serial number, however, a used copy cannot be found to buy anywhere for a long time.