The trick to racking up tons and tons of points
The trick to racking up tons and tons of points in Neverending Boss Battle is to just stay in the corner where your ship is generated at the start of the game, aim toward Sloth’s ship, and fire away. Don’t move about or go chasing power-ups – they’ll come to you eventually – because that corner is the perfect refuge: your torpedoes hit Sloth’s missiles, destroying them before they get near you; and the fireballs always fall just short of your ship. The only thing to worry about is the occasional bluish star-bomb-thingy, but the first time I tried this I scored over 1600 points before I took a hit from one. So basically start, aim, leave something heavy on the spacebar so you keep firing, and go about your business, checking in every so often to make sure you don’t die, because when you do you’ll have to re-aim. That’s all. Nothin’ to it. – Little Washu
Effective use of power-ups
Remember that only two power-ups can be on the screen at a time. Neverending Boss Battle is, by nature, a game of endurance, and so attempting to overpower Dr. Sloth with the split fire, rebounding bullet, or increased bullet rate alone can be very ineffective if you aren’t careful. Instead, pick as many power-ups as you can just to get rid of them until you find the shield or the warp. Since these make you invincible for several seconds, they basically give you free salvos of shots at Sloth that last until the power-up runs out. Rinse and repeat. – BeatZero