Then thing is 'knowing from the start' does not help I'm afraid. If a winner marks it as received when they have not received exactly the advertised game, then the winner will get a tempban on their accounts for rulebreaking - and can potentially miss out on future SGTools protected GA's too. So it's absolutely not a 'being nice or not' thing, a Not Delivered mark is a self preservation thing.

So if you care about a ND-mark, or have any doubts you should really delete the GA and give it away some other way, make a discussion thread, or a jigidi, or something you feel is appropriate

However, as pointed out above; It looks like the game was updated and renamed, not re-released - so your key ought to redeem the correct game. Good luck.

The proper way to check for the winner would be:
1) Redeem the key
2) Click on the Steam-link from this giveaway to get pointed to the store page (make sure that you are logged in for the next step).
3) If the store page says, that you own the game now => mark as received. Otherwise inform SkrittiFan, that you have to mark it as not received, after the timeout period (7 days?) is over. Self preservation, as RCSWE called it.

Answer from developer in a review:
Just wanted to let you know that a few days ago we released a huge remaster of the game called Ultimate Edition. It's a free upgrade for you - just install/update on steam to try it out.