
If you google for Oh! Hajiki, you will find more than 5000 pages. (That was in July 2005, when I first wrote this. Interesting enough, when I repeated the search a year later, there were only 500 results.) Nearly all of them are Japanese. It is very popular there (as a comparison: a search for Japanese pages containing Tetris returned 24000 results), but nearly unknown outside. It dates back to 1988, this older version was for the Sharp X680x0 and can still be downloaded from the author's homepage.
I found Oh! Hajiki fiendishly difficult. You control the red ball with the movement of your mouse, pretty much the way you do in Oxyd. Goal is to drive the other balls from the playing field without falling off yourself. I survived only for seconds.