Pro-tips: #.1 Your multiplier is determined by the # of aliens you see killed with the glasses on (W). #2. Your final score (equivalent to the cash you'll get for the whole run) is multiplied by your HIGHEST multiplier (e.g. 5k w/a 5x multiplier is 25k total). #3. Leaving from the entrance ends the round. #4. Diving out the door (D) is the best way to end the run, as they can still shoot you from behind during the fade-out. #5. Dying takes more than half your money away.
This game is honestly not that hard, it just takes some learning to get all medals.
Strat: Camp in the top-right corner (beside the teller), you'll be safe here, and wait for the six cops to group up on the other side of the desk. Throw on the glasses (W), move down a tad, blast 'em (S), run back up, don't forget to reload (A!), repeat. The grind to 100k (THE GOLDEN RULE), this way, only takes about 16,666 (i.e. 100k/6), that is, if you're just getting the 6x combo. However, after a point the cops will simply spawn and rush to bunch up in that corner, so getting the x13 combo (KICKING ASS!) is just as simple. Keep the glasses on for two bunch-ups and use your special; you'll get the whole OBEY medal sheet easy as f**k.