*** NO NEED FOR VOLUNTEERS ANY MORE. SOLVED BY GRARGAR AND JMICH (GO, GREECE) ***

If you don't yet know what MaGog is, it's a recently-released standalone search engine for GOG Games.
It can be found and its forum [url=http://www.gog.com/forum/general/magog_a_search_engine_for_gog_games]here.

While I'm mostly developing it on my own for community use, there are some (non-programming) tasks I would be glad to delegate to others. Here is the first.

I would like to add (to every game) information about its addition date (i.e. the date it was added to GOG). That information is not publicly available on GOG to the best of my knowledge, so it has to be somehow determined through other means.

As I see it, there are two ways to go about it:
1) Ask GOG for the information.
* Pros:
** Probably easy, if you have blue friends.
* Cons:
** Not sure GOG has the correct info, since their sorting of games by "date added" is all wrong (just checked and it says "Edna & Harvey: Harvey's New Eyes" is the oldest game on GOG).
** Not very challenging.
** Not sure I want to bother the blues. They're rather busy.

2) Collect the information manually, by searching through (a) GOG news releases (on main page and forum), (b) GOG Community Wiki, (c) Wayback Machine for older stuff.
* Pros:
** No shortage of community members enjoying list-making (IAmSinistar?).
** Some community members may already have part/all of the list (JMich?).
** Fun in a sisyphic kind of way.
* Cons:
** Requires perseverance.

So, if there are volunteers willing to do the work (one volunteer, if any, for option (1); up to four volunteers for option (2)), please post here. I will then send volunteers instructions on how to format the data (i.e. a template file to fill the information in).

Is there not dates for each game in the gogwiki?

http://www.gogwiki.com/wiki/Main_Page

Alternatively, there is always JMich's handy GOG Releases list.

Not for all. Silly me. Didn't know about that.
No need for volunteers.

Incredible :O

Be aware that there are a few things missing from that list, mostly the DLCs and the Gold / Special Editions. I should still have the RSS feeds for those, so I should be able to give you a date added, but they shouldn't be more than a handful.
Dracula 5 and the 2 Ednas are missing, since Dracula 5 was added to an existing title, and Ednas were here before, but as one product.

Thank you.
I will introduce the current information into MaGog's database, then contact you about anything missing.
Once I release it (probably next week), MaGog will continue collecting this metric on its own.
I plan to offer users to ability to search/sort by "addition date", as well as by "age on addition" (i.e. addition date minus release date).

Thank you so much for your wonderful spreadsheet. I have incorporated the information into MaGog's database (filling in the few missing ones you mentioned on my own) and it is now available through the search engine, as announced here.