With 500 EUR you'd better stay of from video game market - at least for new, premium releases.
If you're very passionate about video games, maybe you can find a niche in games with bigger profit where your 500 EUR would have higher BP (buying power). I don't know much about these but one way of doing this would be to buy & sell second hand retro games or games to one specific retro console.
There are millions of retro games fans in the world - if you can create good strategy and branding, use some common sense marketing, I'm sure you can achieve great results. And your ROI will be much higher than with new releases for PS3's or xBox 360's.