I was close but when i did in calculator and get the 4,671‬, i thought that this can't be.

War for the Overworld: Crucible GOG
https://www.gog.com/game/war_for_the_overworld_crucible

two1979-1A!82-64###-B!CB!

### : sms writing for "dead" in french
! : was a good hard thriller film

This riddle was almost impossible to decode (for me at least). But after some imploring, @gvyop has provided me with a further tiny clue, and with a bit more neuronic grinding - plus some invisible help from my guardian angel(s) - I managed to decode it at GOG's redeemance portal. :))

Unfortunately, there's still a couple of issues with the redeemable game in itself...

1. WFTOC is already FREE in GOG, so one actually needs NO key to redeem it.

2. WFTOC is a DLC and requires a PAID game (which I don't have, and have no current plans of paying for it).

So, fellow GOGgers - the hunt remains ON !! :)) (just to be totally clear: the key was decoded and became redeemable, but I did NOT complete the claiming process. So that key remains in stand-by).

Good luck y'all...

Oh! Sorry about that. I did not verify this as it was an old key that I received from GOG itself a few weeks / months ago.
Nevertheless, well done for your decoding :-)

And for the others who might wonder what were these little clues that I added in private and who would like to redeem the key completely, these are:
- ### is a form of writing by sound, just letters like in English: "For you" is written "4U"
-! is a film with Brad Pitt, Morgan Freeman

Sierra Police Quest Collection for Steam

###WN-FKV9I-D0***

### James Bond
*** Sqrt of 102400

Five minutes after posting, it was gone... how people do that?

They arrive less than 5 min after it was posted.

Another freebie;

Chasm - Taken

Post here i'll send it in a pm.

I want it. Thx :)

Oh! Good game. Congratulations mate!

Myst Masterpiece Edition GOG discount (don't know how much)

https://www.gog.com/redeem/HNTGEGS5##7Z??L4**

## collectors edition
?? SSD-standard
** a well know class of astromech droids (first 2 initials)

60% off.

EDIT: I did not redeem yours, I received the offer as well.

Deponia

YLGчетыреBA3857E19E8FчетыреD

Got it.
Thank you! :)

Enjoy! =)