But considering that your gf's son is already 10, perhaps you could find out what kinds of things he's interested in and get him reading stuff about that. There are a lot of books out there now based on video games, like:
Halo novels
World of Warcraft Novels
Warcraft manga (I read one once, it wasn't half bad)
If he shares some interest in Transformers with you maybe read some Transformer comics or books with him. And as clichéd as this may sound, the Harry Potter books are meant to be quite good. I've only ever read The Philosopher's Stone and I loved it (a lot better than the film). If he's interested in other forms of fantasy maybe read him stuff like The Lord of the Rings. I'm currently reading "Peter Pan and Wendy" (Japanese version) to my daughter atm.
Years ago I had a year 7 boy whose reading age was that of a Year 2 or 3 student. I knew that he really loved climbing (he did indoor climbing as a sport and he was sometimes busted by the cops for climbing public buildings, like the top of shopping centres); and he had zero interest in reading any of the prescribed English texts at school. So I suggested to him and his father that he should start reading about climbing, which he did. The next year his literacy results improved quite significantly.
I also think it's important to get kids interested in being physically active too. Aside from keeping fit, a lot of studies show that it also helps kids mentally; active kids are found to be more attentive and focused in class and tend to perform better academically. Activities that coordinate left and right sides are said to help with focusing and attention too. Some studies also show that active kids are less likely to suffer from depression and other mental health issues too.
Have you been able to find any kind of activity that he may be interested in? If he's interested in shooting games then maybe just run around the yard or park and play shootings with toy guns. <shrug>
I think the key is to find something that can engage the child's interest. Good luck.
