You should get educated on the many good reasons why a guy in the service would not want to get involved in a relationship ... or why he doesn't want to say he misses you.
In boot camp/Basic training, servicemen are told over and over "Your girl is cheating on you. What do you keep her for? She's in bed with Jody, and having a good time lying to you."
The sad thing is, in MANY cases, this is true. Your guy is probably watching a lot of his new friends go through breakups, divorces, being cheated on, etc. And as he continues to be in the service, he'll see more and more of it. This will scare the pants off of any guy with half an ounce of sense. If all of a sudden all your closest girlfriends got cheated on, dumped ferociously via "Dear Jane" letters, and all they could think was "D*mn it, my boss warned me," you'd start listening to the bossman too.
If he tells you he's missing you or thinking about you, he's showing weakness. It's hard to be in his position, as hard as it is to be the one back home, you have the option of breaking down and crying if you want to. He doesn't. He doesn't have the option of getting too emotional over you; it can endanger him in his job.
It is nothing less than COMPLETELY DIFFICULT to be the significant other of someone in the military during this war. I doubt very seriously that he's "playing games." But he might very well be scared of relationships right now, and it's justified. What you'll have to do is make him trust you. Earn his trust.
Good luck