My wiki has a 2005 entry about MAME emulation of various games, among them Valtric.
I remember this arcade machine from when I was a young kid, on a boat trip with my parents. I was fascinated by the unique graphical design and weapon power ups that attach to the side of the player ship. Never played it, didn't have any change...
I played this using MAME on my laptop, on the train from Aalborg back to Copenhagen. After playing through the *ridiculously difficult* and unsatisfying areas 1-4, and then discovering that there are 4 more stages, which appear to be more difficult versions of the first 4 areas, I kind of gave up on Valtric. It has some style and cool ideas, but I really dislike the infinitely respawning enemies and ridiculous number of bullets. It seems balanced to steal all of your money and nothing more.