why game cant be purchased?

Hi, does anyone want a copy of the dlc for this game? i will trade it for some cards or gems

I figured a brief 'eh' game for $2.50 and I bought the four spare helicopters with a spare dollar so when I started playing it I started to really enjoy it. However looking at the Achievements for Global and seeing that almost nobody has done any of them as well as looking here and seeing no writing, it makes me ask - Does anyone play this game other than me? If you haven't tried it yet, I highly suggest it but if you can, buy either the Night or the Osprey copter when you buy this...it helps so much t...

How do you all find the laser sight for aiming? Doesn't it dissapear at random then you lose track of where you're aiming? I find that the worst bug about this game, and it prevents me from enjoying it and completing it. It's really a shame, I played this on Commodore 64, and was thrilled to see it in HD, now it's just a pain to play....

It says I got the achievement in 2012.. how do I get to the Zombie DLC in the game now? Thanks.