Some locations have major video game centers. There are tons of free used novels to read. I always recommend soldiers carry a primary novel on their person and a secondary novel in their gear if they are traveling. It is not always convenient to get into your gear and pull out a laptop, but a novel can be easily slipped in and out of your cargo pocket.

I refined my programming skills developing a personal open source software tool over two deployments. Two deployments was almost enough to transform me from a junior developer into a strong senior. I also passed the CISSP exam on the first try because I had time to read the entire course book and think about the qualifying management scenarios.

You absolutely have to find a way to say busy. Boredom reinforces your loneliness and lack of emotional intimacy, which is a bad place to be in.