damn:
a. i've started playing with the intention to score, and it's much deeper than i suspected -- i think it must be possible to keep a chain going through the whole of level 1, though there are a few spots i haven't figured out. and by extension, i bet it's possible to keep a chain going through the whole game, bosses excepted
b. arcade++ mode is where it's at as far as scoring goes. i just scored 4.5 mil, and i only got as far as the beginning of stage 2. it can be frustrating since one hit kills you, but it replaces the 10x multiplier with a 30x multiplier. and actually the game is a lot more exciting without that big cushy margin for error.