Did you try PapiJump ?

With Deep Thought's help, I modified it : now we have two modes, port and sound. 
At beginning you can choose between both by pressing P or S.
Port mode:
 • Ball can be drive by port. Contact with ground and pin1 on the jack make ball go to right, contact with other pin make ball go left.
 • Contact between all pins start/restart game, and while playing it opens the bugged sprite editor.
Sound mode:
 • It plays a little melody while playing, another in game over, and a sound when hitting a bar.
 • Sounds are bad, but I don't know very well Axe interrupts; and game is slower.
  Don't connect headphones while playing in port mode, it will make game over or other things like this ...

I hope that Deep Thought will can upload it fast.
Thanks to him and to Axe Parser.

Enjoy ! 

I was going to make a circuit to play by port (why not) but sound doesn't work so I didn't want to try port. Is the one uploaded on oct 5 the one with port play?

zero44 asked me to upload it for him (we passed the files back and forth in email), but I couldn't get it to work

Okay, I know this is really late (and especially apologies to zero44, who sent me these files in October), but I got it working. It seems like one of the files zero44 sent me got corrupted some how; that's why I never managed to test it and post it here. It was actually a really quick fix, so here it is!

Everything beyond the core of the game (released a year ago) is zero44's work. I'm honestly not entirely sure what it does, but apparently the modded version has two modes: P (as in Port) and S (as in Sound). You can test them in WabbitEmu with sound enabled (Calculator > Enable Sound). Press 8 (P) and LN (S) to toggle.

I'm curious what port means, though, there. Do you need special hardware to control the ball with the port or something?

I think it runs through the I/O jack, and could theoretically be run using an accelerometer...

I just have to say this is AWESOME and I have plans for making a controller for it

*Bump* I tried to get this to work on my TI-84+ SE. When I set it to sound mode the game just hangs up when I insert headphones. When I disconnect them the game unfreezes, displays a smiley and exits when I press clear. It behaves the same way in port mode. I'm running one without the xtra Ram. OS 2.43.

Have you made this poorman's accelerometer yet? I actually thought of this last year and I even made it and it worked with my version of papijump: TI jump, but it was very unreliable. The little rod kept getting stuck. I think it's better to use an accelerometer with an I2C bus so you can interface it with the linkport.