I've recently been finishing my 4 player Pong game for PC (because I now know enough to do what I want to do). Shame it can't have netplay, but that's a limitation of transferring data. Even at the fastest theoretical transfer speeds, programming Pong to work with lag properly (as in, will work without disgruntled players) is literally impossible (at least, with current computer physics). That might sound stupid when you see Halo doing "just fine", but the truth is, Halo (etc) use some very nifty (and incredibly complicated) tricks to make it seem like you are synced up. But the reason these don't fail you completely is because the speed and nature of games like Halo mask the larger issue. With my Pong game, the ball can travel 2000 pixels a second over 800 pixels. Any lag at all cannot be compensated properly at those speeds and with a game like Pong.
In any case, this Pong game isn't your run of the mill Pong game. It comes with a mini game, ability to change to custom graphics, 4 player (including joypad and force feedback) support, and has a myriad of options and settings. I'm trying to create the best freeware Pong on the net. Because what is out there at the moment is badly programmed garbage, generally. Nearly all the one's I saw made the same mistake of thinking diagonal speed is simply x:=x+1 / y:=y+1. That will actually mean the ball travels faster diagonally than it should.
Programming wise, it's a hobby. I've added music support (and will get my mate to make some music for it) and may need a catchy tune or two. Unlike the other game, this one is fun to play long term, and programmed far superior to it too. The downside is that my graphical abilities are crap. So maybe I can enlist someone who is good with graphics at some point (like I said, there is an option to add your own in from a folder).
Here is a screenie of the 2+ player option screen as it currently stands

I'm currently programming the computer player AI. Lots still to do, but the meat of it is there.