The "KAI" from the title stands for the 6 extra levels added to the 6 originals from the arcade. And what levels!!! that's a tottally different game from there, NAXAT powered! Everything blows up all in a sudden, level-up ship, awesome music with fantastic drumset, upgraded graphics, and huge amount of sprites and bullets everywhere, not far from a manic!
Without the 6 first levels, would have been top 5 on PcE, but there's a cheat to start at level 7, so ...
This shooter is no different than the arcade version. The only difference is the plain you fly and a couple of graphic changes. Other than that, there is very little difference from teh arcade version.