Greatest Valve game

[Zenthos]

Portal, I had the funnest while playing it but probably the least replay value.

TF2 with replay value.

[Ad Bot]

[Khorde]

Half Life 2

[_Rebel_]

So clearly your including mods not made by Valve, but based off the game.
But I will go with L4D2, and I haven't even played it. (Only L4D1)

[Robo Noob]

My favorite is none other than CS: Sauce, but they seem to have really out-done themselves with L4D2.

[Leafsoo7]

half life

[tikitai]

Half Life

[CC]

Condition Zero Deleted Scenes.
And Half Life: Source
If you haven't realized by now I'm joking since they're the two worst Valve games, and I actually favor TF2 over anything else.

[Regulith]

I'm torn between HL2 and TF2.

HL2 because of the graphics and the game mechanics and TF2 for the replay value, even though you never really "play it through".

[General Nick]

Half Life, Half Life 2/Episodes and whatever the latest game they have going which usually has the bestest of graphics and stuff.

[ChexGuy331]

classes required skill to use

Looks like someone only uses unlocks.

[snot2]

tfc is too fast, everythings happening all at once

[Dusty12]

Choice is obvious. Half-Life Franchise. It's not a mindless killing game like other well-known titles, such a TF series and L4D series. It has a plot, backstory, and drama in a way.

[Bob777]

I say Portal.  It's really great, it's original, fun, and was well made.

[Sandvich]

l4d2

[MtnDew]

Ricochet lolololol

Choice is obvious. Half-Life Franchise. It's not a mindless killing game like other well-known titles, such a TF series and L4D series. It has a plot, backstory, and drama in a way.

lol

lol