I've used Etsy before and it's a legit. Look at the seller's account and the feedback to give you a good idea if you want to purchase from them or not but also be cautious because you never know who might be a scammer with fake reviews. Overall, it's a pretty safe and reliable site.
Edit: Looking back at your post makes me want to say that my comment is for the majority of etsy sellers as they're usually people selling their own products. Someone selling games is a little different as it's selling someone else's product. I suppose you approach it like ebay or something.