Open 7400 Logic Competition

I was reading HACK A DAY yesterday and stumbled across this design contest using only 7400 logic series chips.  Reading through the rules made me feel nostalgic of my intro to computer engineering class.  So I started coming up with projects to do, clock, calculator with a full custom keyboard, game of life... all the standard boring stuff that's been done a hundred times.  I need something different, something that I would not only enjoy building and showing off to my friends and parents but something I can revisit and get enjoyment out of again and again.  Something people would want to see b/c it can give them entertainment and not just a "wow, you built that... that's neat".  If you haven't been following I'm talking about a game.

But what game?  Well, I have already come up with it but I don't want to tell you what it is, not yet.  All I will say is it will have 2 buttons, a switch and a lot of LEDs for display.  I have a LED matrix laying around from a project I did years ago that I may be able to use.  How to drive it w/o an MCU will take some thought...

I will only use 7400 ICs, not the 7400 series only the 7400 chip.  I could build the game using some of the more complex 7400 series chips with relative ease, but I am looking for a challenge.  I don't want to simply throw in a memory chip, I want to design a custom memory board or boards using the nand gates to construct flip flops for each bit I need.  I reason I need 10 bytes of memory for this game, using 7400 chips I can build a simple D-flip flop with as few as 5 nand gates or 1.25 chips.  This works out to 10 chips per byte so 100 chips just for the memory!  And that's just for the memory, not including the inputs, display driver, oscillator... this will be a challenge!

I will also do it as open as possible.  That means all open software for designing it and publishing all the files as well as lots and lots of pictures.