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Actually, you shouldn´t need any help with this game since it all speaks for itself. But if you feel like you need a guide, here it is:
Abstraction
Beat the game
Simple, just follow the game all the way to the right until the game becomes extremely blurry and and pixely. Continue until the medal shows up.
Imagination
Read all the signs
Just walk by all the signs. It will count as read when the text pops up in a purple box. There are 16 signs to be read in total.
Appreciation
Get all the coins
There are 200 coins to be collected in total. Collecting them all requires some backtracking although you can cleverly make use of the fact that you can jump much higher after you jump on an enemy. This could possibly save some time.
Predestination
Kill all enemies
Kill all the enemies by jumping on top of them. There are 45 enemies in total.
Juxtaposition
Don´t take damage
Don´t get hit by any enemy during the game. Just try to avoid as many enemies as possible. In that one part where many enemies are walking on one platform, simply wait until they walk in line and keep bouncing on top of their heads until they´re all gone.
Just a tip: When you have missed a certain medal, you can always walk back to collect all the stuff that you were missing. This way you can avoid having to play the game all over again from square 1.
Haggard
Hm, I've read 15 signs twice now, but no medal. :(
And I don't think I miscounted or missed a sign.
Auz
It could be that the amount was actually 16, because I just counted and didn´t go for the medal.
A last sign must be somewhere very near the end where you can hardly see it. So just walk around there a bit.