First attempt (I shit you not).
ARCADE - NORMAL
Icarus - 329,267,900 - 20:17:93 - ALL - 91%
I reckon you can get over 500mil in Arcade Mode, Normal difficulty.
The game's quite easy once you get up to speed, though.
By the way, does anyone know what determines your progression through the Darius-ish powerlevel grid? Some of the final levels are pretty useless, some of them are awesome for scoring.
EDIT: Actually, scratch that. Following on from the above, on the second credit I discovered a very bad design fault that leads to a very easy scoring exploit, and the result is that the score counter in Arcade Mode can technically be
counterstopped at 999,999,990, if extra digits aren't added (which I doubt, given some of the design flaws in this game). Not only that, I can get the game to the point where it crashes because there is so many powerups generated upon a death that it cannot cope - on the second run testing my ideas out, it crashed on stage4, when I died twice and spewed so many powerups that Windows kicked me out of the game, with 705mil on the board.
Arcade Mode is broken for scoring. Looks like Challenge Mode is the only worthwhile mode in this game.
By the way, if you guys want to record replays, FRAPS works with this game.
EDIT2: Red and blue pods affect the powerlevel grid - if you have more red powerups when you level up, you go up the grid, and if you have more blue ones, you down down the grid. While it's an interesting take on powerlevels, some of the maximum level attacks are completely useless. I think the amount of bullets you fire affect the Bullet Bonus counter - the Hibachi-style screen-filling attacks seems to score a lot better than some of the spread attacks.