I need help on dealing with my girlfriend's spoiled son.

Hello. I love my girlfriend and I love her son. However, the kid has a problem. He is spoiled, like no child I've ever seen. He is 10 years old. Just to understand how spoiled he is, recently he got a gaming computer. We tried to have the following gadgets: webcam, sound columns, gamepad and headset. The store didn't had the headset but we bought everything else anyway. The first thing he says about the computer is "where is the headset?" When his father called him and asked him about his computer: "It doesn't have headset."The same thing happened with games. I was instaling several games in his computer that he asked: minecraft, paladins, team fortress, wow, wich he loved them all. He wanted GTAV, I tried to instal it but I couldn't crack it. He was upset and almost started crying, so I shared my steam library with him (over 70 games) figuring that we would find something he liked. He still wants only GTAV, and only stoped when his mom promised him it by christmas.The problems get more serious than this... Last week, 4 of his dinner meals were pizza, because he don't eat anything that he doesn't like, and he likes very few things. The mother needs to put him to sleep everyday and most of the days be there with him until he falls asleep. He needs to eat at night baby cerelac or he gets realy upset.At first I tried to unspoil him by trying to do little things, like chores, some punishments here and there like no playing computer if he acts bad (he played in mine before he got his). But I feel the mother doesn't give a damn and even gets mad at me if I try to educate her son in a diferent way, so I just stopped.Some days ago he left his underware full with poop in the WC. This happens like once every month. I talked about it to my girlfriend about it, she said "I will talk with him about it" but never did.I love my girlfriend and I do realy love my life with her, though I don't like how she educates her kid (since I don't want any kids of my own I'm not looking for a good mother). And I also love her kid, and love how I do a positive impact in him sometimes. I played videogames with him, talk about pokemon (he asks me "how was pokemon in your time" and makes me feel old xD), I showed him my infancy movies like star wars, jumanji, terminator 2 and he loves them and talks about them so much after seeing them, I love that feelling of passing to the other generation something that was good in mine, and see the same effect.But I just don't know how to deal with he kid and the mother when it comes to how spoiled he is and how he doesn't show any sigs of growing up. I need some guidance, some help and some ways that I could make things better to everyone. What should I do, how should I talk with him, is there any trick that could make things better to our life in general?Thanks in advance for your opinion and for listening to me. via /r/Parenting http://ift.tt/2ecMfix