This is concerning something else though.
I also own a pndoras box ex2.It came preloaded with some DC titles the majority of most run terribly but Ikaruga runs oerfectly.
It is DC based as it has the splash screens etc but the backgrounds in game are full 4 x 3 and have much more detail .
horizontal mode 1

Horizontal mode 2

Makes the game seem way more interactive to me.
Been trying to replicate this with emulators and on the DC itself but to no avail.
This 'has' to be a different release ?? I can drag files from the box but they're encrypted in some way so there is no way of playing it on an emu or on the dreamcast itself - just produces errors .
I would love this version running on original sega hardware but can't find it anywhere - is there any other release apart from the official Japanese one ?
Apologies if in the wrong forum area but I'm new here.
Regards , Matt.