Today i was charged for almost 49 eur for a purchase of a game. It was not written that i have to pay it. How do i get my money back?

What does the game's description page say ? Does it mention in-app purchases ? Subscriptions ?

Purchases are considered final but you could try the 'report a problem' page to contact iTunes Support and see if they will refund you as a one-off : http://reportaproblem.apple.com

Or you can try contacting iTunes Support via : https://support.apple.com/contact or https://www.apple.com/emea/support/itunes/contact.html