To go to Haven you need to advance a little bit in the game. After finishing the missions from the first area, go to the north and you see a clockwork place with a level at the end of the path. Do the level and welcome to Haven.

Now in Haven, go to the north and you see the arcade.


In the arcade, now choose the level with a:

Eagle icon:



Or a Horse icon:







Complete the level (be sure to finish the level in the clockwork zone)

If you have well follow the step of the guide.
You should get this achivement:



(TF2 Hat): After the achivement load up TF2 and you should have a notification.

Click on that you get this hat:















I hope you enjoy my first guide, I am not english so if I badly write a word im sorry and I like if I get a rectification. Have a good day/night and I hope I help you with something :)