Sales (and refunds, if any) are handled by the Apple App Store (for Apple games), and by Amazon and Google Play (for Android games). We provide games to those stores, they handle the money.
For Windows PC games, I cannot provide refunds for any downloads. There are two reasons for this:
1. When you purchase a download game, You are emailed the unlock key immediately. Which means you have the game on your computer. If I gave you a refund, you could still play the game.
2. I allow 3 days of free trial on all games. So you can decide if you like it before you buy it.