Played from start to end. If I didn't get horizontal helper as my first one, I think it'd have taken like 3x as long. The upgrades give much too little bonus, and by the time they're reasonable prices for the speed given, you're in the quintillions of money due to depth multipliers. One radius to get the four neighboring tiles, then gotta get to floor 11 to benefit from it more. Possibly "neighboring tiles" would make more sense than a simple radius.