Tip : Never live a city when you still feel really uncomfortable with the enemies there (With patience comes Victory)
I finished this game in 35 mins with this trick (And choose accurate weapons they are the best for you ; and leave other weapons for survivors)
Papa i hate your games and badges and quests that want you badges
But for those who got the Yo Dawg quest this is really easy compared to medium badge from freezeria
Spoiler so read if you stuck like me or just want to finish fast::::::: To finish the game you should get license 4 and upgrade depth to max (infinite) and start swimming down till you reach an strange place and an message will show up::
Stalagmite : Stay on top of screen using jump arrows on top and then fall to the pit spikes
Stalactite : use right side jump arrows and hit the spike above it
+ if helpful
To get hard badge do exactly as askon said But play mission 38 instead of 35and bomb the U spot at the end of maze (Also don't ever get lower upgrades and save upgrade points and upgrade the ultimate one first ; and for make upgrade points start playing level 1 and place 2 basic towers on the first reverse U spot and hold N and use one small bomb at the curve of the reverse u when enough enemies gathered there and do that again (You gain 24 upgrade points every time you play so you should repeat 84 times to get Starting cash 2000 points upgrade after that you earned the starting cash upgrade go play level 2 and start spamming small bombs (click on bomb or press z and hold shift while clicking) and with this trick you should start getting all bomb upgrades as well as money per kill upgrades and advance to a higher level for spamming your bombs when you felt comfortable and as i mentioned before don't play level 35 cause its impossible to pass the level while spamming N)
This game is good but really lacks in difficulty
I stuck at level 36 for sometime because of thinking about a hard way to solve the Level but apparently it was super easy