First game you ever bought on steam?

21 August 2007 Condition-Zero $9.95

Worms Reloaded, when it first went on sale. I only bought boxed games until then. :)

Steam member since: 2011-10-10

Grand Theft Auto Complete Pack - £4.99

It says

"Half-Life Platinum Pack - Complimentary"

without any date, but I registered my steam account just for that, so it's probably the same date

Member Since: March 23, 2004 (nearly 8 years on steam now! ;D)

November 12 2009 COD MW2 Retail 50 USD

June 11, 2007: Half-Life 2 Game of the Year Edition

20 Nov 2009, Infinity ward screwed up(or maybe it was intended) and i was able to play MW2 cracked on Steam, a few days later this was fixed so i decided to buy MW2 retail and activate in on steam

31 may 2008
Race07 Viva Media Retail Boxed

1 Nov 2007 ---- Valve Complete 2007 Pack ---- $118.94

Then I bought no other game till 11 Jan 2009 when I bought X-Com Complete Pack

Sid Meier's Civilization IV Complete.

Member since: February 4, 2006

Counter-Strike Source

Nov 1, 2007
Valve Complete 2007 Pack

However, been a member since July 4, 2007 as a friend of mine got an old account VAC banned :(

June 20, 2007, Counter-strike anthology

7 November 2007, Counter Strike Source.

HIB2

Member since: May 7, 2005
First game registered: Half Life Platinum Pack (it was just a box copy of CS, though)
First game bought on Steam: Mirror's Edge.

Member since: Member since: August 10, 2008
First buy: 26 Oct 2008 Team Fortress 2

Orange Box (retail), December 15th 2007.
Online (via Steam itself) it was Magicka Complete on the day Magicka Vietnam was released.

11 Juli 2011 / 54,98€ Einkauf / Valve Complete 2011 Pack (DE), Battlefield Pack - June 2011

2 Jan 2008$12.44 Purchase Garry's Mod
But bought CS:S 2007 from another store.

7 Oct 2010 $10.19 Purchase Left 4 Dead Bundle

November 19, 2009 Counter Strike: Source 20 €

Killing Floor.

Oct 10, 2007 - Free - Purchase - ATI Half-Life 2: Deathmatch / Half-Life 2: Lost Coast Promo

That was my first Steam game on this account, first PURCHASE was...

Feb 25, 2011 - $4.99 - Purchase - Command and Conquer: Red Alert 3

Everything between that was me collecting free games/promos that I never played.

Member Since: July 6, 2008

January 2, 2010: Eidos Collector Pack ($49.99)

My very first thing that got me a Steam account was the Orange Box, but I got that from Best Buy.