I beat the game like every 3-4 tries but only managed to get the highest score 3 times. Having a good early game is the most important thing for highest score. If you have to use a heart scroll before having 8 Max HP it's pretty much over, you can still beat the dragon but you probably won't get 365 points. So you need to find a gold chest and the egg or two chest in the early game and ideally a heart scroll. Everything else like the rat king or slime wizard is nice to have but not really needed