SGsAP (explanation posted)

Explanation:

For the most part, all these codes were the 5 letter/number code that you can find in each giveaway link. Example:

steamgifts.com/giveaway/Qw5Sm/bad-rats-the-rats-revenge

I think most everyone got that. There were no giveaways that were hidden in any way behind any puzzle. It was all laid out for you all. The codes that did NOT link to a giveaway were the headers for each individual column and there were several boxes in the right column with unknown codes. These codes were all in base32.

https://emn178.github.io/online-tools/base32_decode.html

Headers Translated:
NF2HG= its
MFWGY= all
ORZGC43I= trash

This was a subtle, but very well-hidden hint, that the giveaways within each of their respective columns were all trash. They all came from previous Humble monthlies. Now, the unknown codes in the right column actually hinted to something more substantial:

Translated:
KRUGK= The
IFTHIZLS= After
KBQXE5DZ= Party
K5UWY3A= Will
IJSSA= Be
ONXSA= So
NRUXI= Lit

Now, I didn’t expect anyone to understand this, as you’d have to be thinking fairly outside the box to make the connection, but it doesn’t matter in the end anyways. This leads us to the thread’s title: SGsAP

SGsAP is an acronym for a steam group I created for this event that stands for: “SG's After Party”. To get an invite all you had to do is bump the thread with a song. For those users that participated, I used the whitelist tools wishlist feature to figure out what the top two wishlisted games were and made giveaways for them. There'll be more giveaways down the line too. Feel free to decline the invite if you'd rather opt out of this part :) Oh, and the intentionally left blank box meant nothing, I was just making myself laugh.

Edit: I scrapped the group idea, now it's a temp whitelist thing :D