My first try - Can you find it? (ENDED)

I want to give someone my Metro Redux Bundle steam gift and I want to try something else instead of a public giveway.
So i try to make it a little bit more difficult to enter for my new giveaway.

I've heard, some people like a little challenge ^^
EDIT 1 (07/09/2016) The ga ends in ~5 days and I will add a hint here in the description in two or three days.
EDIT 2 (07/11/2016) Some had a problem with a certain answer. Here's the hint: It's not one ;)

View attached image.