People who won't redeem games

This is your friend before send it

http://www.sgtools.info/activation

They have one week to mark it as received, don't worry! Also make sure to check for inactivated wins before sending the game.

Sometimes they just don't care. There are users who just click to enter literally everything, but when they win and realise that the game doesn't even have cards, they just don't bother to get it or even say they don't want it. There aren't many weeks where I don't have to chase around some winner to get their gift finally if they won it.
Assuming the dear user didn't ran away with the key to sell or regift it. It is advised to check the winners for such behaviour. If they have a record of just yanking the keys, you can ask the staff for forced received feedback if you provide evidence you sent it.

Doing puzzles and/or making it bit more difficult for people to enter does cut down on the "chasing" aspect. However, if you're into doing public GA's, I've heard that adding winners on Steam and giving them the key there cuts down on "unredeemed" wins. Me, well I've stopped chasing people down and just wait the seven days... I know it's frustrating but unfortunately that's just the way it is. Some peeps are good about marking wins and others are not. But as others have mentioned, definitely check SG Tools before sending any key....

sometimes they're on mobile and don't have access to computer,it happens when I do level 4 gibs too.

just saying... the higher the level you put in your ga, the less issues you will run into. :3

anyway, remember winners have 7 days to mark as received and activate their games. if that doesn't happen you can ask for a reroll (it's risky if they saw the game key, because they can activate it at any time -.- ).