use the following to get hard badge:
day 1: all about luck, try to get at least 2 000 by staying alive as long as possible. Use money to upgrade radar, fuel sucker, fuel tank, rest of the money evenly into left / right rockets and launcher.
day2: use radar and rockets to stay alive as long as possible, if you can survive 5 minutes you can get hard badge easy. Use money to upgrade launcher, e-rockets and comrades as best you can.
day 3: no need for rockets, drop comrades at 0 feet, if you run out of speed used e-rockets to get to mars