There is not much to specify for the question, its really simple: Which title is the first game you have purchased on Steam? Was it a good decision? How much did you pay? When was it and what device? You don’t have to answer all questions, this is just a fun discussion to have.
You can check your history: https://store.steampowered.com/account/history/ Edit: Some in the comments pointed out that the purchase history doesn’t go back all to the beginnings of Steam. So if you purchased something earlier, it won’t be listed on your account.
(I reply with my game too.)
Cod mw3, which is why i made my account. I think. Maybe it was for that time when l4d2 was free on christmas, whichever came first.
Edit: I checked with the link, mw3 came first. Though it doesn’t show up in the list because, being a teenager with not a lot of money, I got it from a keystore. The first one in the list is l4d2, which as mentioned was free, then the first one I actually bought through steam was audiosurf.