You can win codes for Letters from Nowhere 2 if you follow G5 Games on Instagram: http://instagram.com/p/oOQRvdSRGB/#. Fingers crossed "Follow @g5games on Instagram and win a promo code for Letters from Nowhere 2 (iPhone/iPad). Five random people that follow us will win a promo code for the full version of this mysterious hidden object aventure. The winners will be announced on Sunday, May 25. Good luck!"
As far as I know, the contest is held on Instagram only. But I think you can easily set up an account on Instagram.