A game you entirely don't regret purchasing

[Zabriskie Point]

Portal. But I got it when it was free on Steam, so...

I still play it every day. I've beaten the story mode 20+ times, gotten gold on every advanced chamber, and downloaded countless map packs and mods.

 

[MrTub]

Crysis 2, WoW, Diablo 2 and a lot more.

 

[Amethyst Wind]

Project Sylpheed.

Really.

I played it through 10 times and loved it each time.

I got it 2-3 years after it came out too, so not even full price.

 

[Vern5]

Fallout: New Vegas. It's like being the Lone Ranger, Bear Grylls, and myself (a born gambler) all at once!

 

[Hiphophippo]

In terms of strict value for my money (if that's what the confusing thread title is saying) I'll have to say Team Fortress 2. I actually picked it up outside of the Orange Box for 10 bucks. Let's just say I've put a "substantial" amount of time into it.

Really, I guess the only other thing that comes close is Duke 3D way WAY back in the day. With all the maps I put out for that game and all the modem to modem multiplayer...sheesh. Lots of time.