Your First Steam Purchase

My first Steam game was the original Half-Life, but that was before Steam existed. I had registered it, so when Steam launched it already had it in my account. The first game I added to Steam was The Orange Box, but that was from a CD-key. The first game I bought on Steam is a tie between Peggle Nights (I had been enjoying the crap out of vanilla Peggle for months) and Brothers in Arms: Road to Hill 30. I bought them the same day (Halloween, 2008).

Bioshock 2 preorder with Bioshock 1 was my first on-steam purchase. First purchase of a steam game was The Orange Box in '09.

Fallout New Vegas Ultimate Edition.

CS:GO

Braid, one of the best games ever

Half-Life 2.

The team fortress 2 and garry's mod pack. Back in the day when tf2 weren't free.

Team Fortress 2 in March 2009

Was introduced to Steam through a retail copy of Portal, but apparently Ecco the Dolphin was the first thing I got through it.

I installed Steam to play Left 4 Dead with friends. Zero regrets. Many deaths.

XCOM: Enemy Unknown pre-order. :3 I don't know why. XD

If I remember correctly, it was Saints Row: The Third.

Half-Life 1 Antology 2CD (but i am got key for Counter-Strike 1 Antology).

The Binding of Isaac+Wrath of the Lamb DLC

Well first game I got as a gift on steam was Ace of Spades , but the first game I bought was Tomb Raider 2013 as pre-order

Mine was Terraria

TF2 when it wasn't F2P... shame on me

Mark of the Ninja.

The Counterstrike: Source + Garrys mod bundle.
I have a friend who used to be owner of a big Garrys Mod community, and he showed me what it was all about.

Back in 2010 I bought Mw2 retail but my parents didn't let my install steam to use it. Bought my first computer in 2012 and finally got to play it...

It was either TF2 or The L4D Bundle. I had portal before that, but I got it for the brief period when it was free.

STALKER: Shadow of Chernobyl - Holiday sale 2009.

Aliens vs Predator Classic 2000.
I had just started using Steam (had an account from way before) more regularly as Valve was giving away Portal for free so as I was playing that I noticed the classic AVP was getting released on steam and I just had to have it. A whole year later is when I bought my next game, winter sale - Deus Ex 1 + 2 and FEAR. All old games that I loved. The Orange Box soon followed as I had to own HL2 which I only pirated before and I wanted to try TF2. L4D and Oddboxx came soon after and I had lots to play.
That's what started my PC gaming collection on steam and when I gave up game piracy. Good guy Valve just had such an awesome service it turned me. Being a PC gamer for over 20 years, I had only just started buying PC games 3 years ago. Steam and Humble Bundles helped.

Half Life 2 Gold Edition... 10 years ago xD

Half-Life 1 Anthology.