So I had the impossible badge and here is my opinion for the difficulty scale:
Easy:
Boss 1 (Just keep on focusing on oncoming spiders.)
Boss 2 (Make sure you have a bomb to use at around 7000 boss health.)
Boss 5 (The hard phase of this boss comes early so I suggest you use the bomb early.)
Boss 10 (The health boost isn't that major.)
Medium:
Boss 4 (Have a bomb at the ready, Ok so when the four minions are summoned use the bomb to kill off the minions.)
Boss 7 (No real tactic here, it just takes practice but even then the rocks can be a bit annoying sometimes.)
Boss 9 (Same as 7 but when the minions show up just shoot them down straight away.)
Hard:
Boss 3 (Have a bomb to use to speed this up but when the eye is underground, start from the side of the screen and move slowly towards the other side to avoid the yellow bugs easily.)
Boss 8 (Like Boss 2.)
Insane:
Boss 6 (And finally the boss which in my opinion is the hardest on endless insane, you might as well start over).
Would prefer the reset button was the middle button, srysly how frustrating it is every single time I unintentionally press the 'more games' button. Alternatively 'r' to restart.
Everyone go here and fill in the form if you want to get the badges after earning them:
https://www.kongregate.com/feedbacks/new?game_id=896&type=MissingAccomplishmentFeedback
For the hard badge, try and get up to 200 metres (note that while the laser is fast, even small leaps are fast), then from 200 - 300 metres focus on only performing small leaps (Just lightly tap the esc key as the laser will STILL fail to keep up unless you waste too much time), finally for the last bit, do small jumps but also fit in a high jump somewhere to avoid parts where there are massive hazard on both walls, then you are done.
The controls are a bit floaty at first but to get the impossible badge you should try to make light movements for swerving past the obstacles instead of making big movements or else it will feel even more floaty. This will take some practice but the impossible badge can be obtainable keeping this tip in mind. OK, that's it.