How do you justify your gaming-related expenses to your relatives?

I just don't spend real money on steam. :P Trading helps me to get profit and I don't have to use real money.

simple, i don't :)
my money iz my castle :p

I live with my fiancé. He likes to game as well. I have no problem with this at all. But I feel for you, it sucks feeling so dependable and restricted in your own home.

Well the best course of action would be to get a part time job somewhere. Something you could do on weekends or whatever fits your schedule. That way you could flip em the bird when you spend on what you like (gaming!) if they try to give you **** for it, since it's your money!

My gf doesn't care how much I spend on games, since she directly benefits from it she's cool with it lol she likes to watch and play with me if it's local co-op. I don't spend that much to begin with, maybe $30-$45 a month if I'm feeling frisky, but then go several months at $0

I tell them the truth, and I have for at least 6 years. I am 20 now, but five years ago, when Skyrim was about to be released I was only 15 (maths), and I asked dad to get me a pre-paid Visa card with 60€ on it so I can buy a game I really really want. It was my money that my aunt gave me, but still. For two years I have been earning some money online, sometimes huge amounts and sometimes tiny, but still I earned a bit. However, business has stopped around summer last year and I was left penniless, pretty much. Because I was used to spending so much money that now when I have small amounts of money, I spend them like I have at least a few hundreds on my bank account. Don't want to make this sound like boasting, because it's not, and I'm going a bit off-topic, but shortly after I stopped earning money I won big on lottery (enough to buy myself a better, 20 years newer car), a few other things, and to give a bit into the household. However, before you know it, I spent all of it and again - I'm penniless. And lo and behold, Witcher 3 goes on a sale - the game that I wanted for so long. Not a huge sale, it was still 40€ if I recall correctly. I simply asked my dad if he can give me that amount of money and - quite surprisingly - he didn't object. Also, I'm still unemployed but have signed up to be a police officer, so we'll see how that goes.

TL;DR: Tell them what it really is. You are a grown man and you can't be lying to them about such meaningless things. They will respect you more if you say the truth. I pretty much always tell them the truth, even now when I get any amounts of money they're usually gone within days, and I'm not lying about what I spend them on - going out, games and car stuff.

hmm, I lived at my parents until I was 22 and I was gaming and surfing the web and feeling quite depressed back then. But when I moved out, (my parents moved and the new place they moved into simply had no room for me ;) I had to get off my ass and fast and lived with a friend in our own rented flat and I got a (badly paid) job and astonishingly everything got better!
I even started doing sports and game less and I felt so much better after a short while. it really turned my life around. two years later I even had a girlfriend ;)
Don't know if it helps you, but I think even forced exit from home, can have a huge positive impact on your life. So maybe there's a job to be gotten far away from home and a way to life there maybe together with others in a shared flat.

I think you could explain gaming expenses in categories like going to the cinema. But when you watch a movie for, say, 2-3 hours, usually gaming experience lasts longer.

well i dont i am an adult i have my own money i always pay my bills never owe money so for whats left i do what i want :D