Go-karts. Been a while, and actually too long ago. 
Rossell wrote:They've presumably been making Half-Life 3 ever since Episode 2 come out. In true Valve tradition, there'll more than likely be a rumour/announcement that they've thrown everything away and started again like the last two games. The episodic thing never worked out so more than likely HL3 will be the title.
As for what we'll see or when we'll see it, I don't know. A couple of things need to happen. Valve need to create Source 2 to power it because Source as good and flexible (see Titanfall) as it is, needs a heavy update. They also need to give the game something that'll make it absolutely unlike other games and advances the genre. Half-Life 1 bought full on storytelling and action set-pieces to the bargain. HL2 upped the emotional stakes and introduced physics into gameplay whereas before it was a novelty.
My money is on drop-in, drop-out co-operative play done right.
if it's a next gen title then I'm sure they'll use a brand new engine for it. Man, imagine Half-Life with next gen graphics. Mouth watering. I know it's a nerdy thing to say.
