I've finally been able to bring together many of the components of my 6502 system to support a retro-style game. The game will be a work-in-process for a while. I know the game itself is not impressive, but I'm quite happy that all of the pieces are coming together to support this type of game (and the basic mechanics of retro gaming). Key components for this game to work:
6502 core system
Sound card with joystick support
VGA output (800x600)
Here's a video of where I'm at with the game.
If you're interested in more details of the system, I have posted an updated overview of the complete system. See My Frankensteined 6502 - Five Months In.