Your First Steam Purchase

I think it was Storm in a Teacup

cs 1.6

Killing Floor

Portal 2

Portal

Half-Life Platinum Pack in Feb 2007 because of CS 1.6

First game I had on steam - Portal (the first one, free offer with mac release)
The first game I bought for steam - Skyrim
The first game I bought on the steam store - Oblivion (yes, after skyrim.)

call of duty 4, still playing.

L4D

TF2

My first was Left 4 Dead 2.

The Orange Box

Left 4 Dead 1

Counter Strike 1.6

In 2013, it was Dark Souls: Prepare To Die Edition for %10 ;)

Europa Universalis IV autumn 2013

Counter Strike 1.6 - No regrets!

Chivalry: Medieval Warfare

Half-Life 1 Anthology. Long, long time ago...

TF2 when it was my first steam store purchase [$2.49 on halloween '09]

Though I had HL2 and CS:S retail that started my current account.

Killing Floor in 2010 for 3.99 usd

Overlord Complete Pack. :c

Serious Sam HD

Killing Floor + DLC

The Orange Box I bought retail, and that's how Steam got on my PC.

My first purchase on the Steam store was (everything listed was bought in the same transaction, so I can't list only one game): Half Life 1, Half Life 1: Opposing Forces, Half Life 1: Blue Shift, Arma 2 Combined Operations.