Dear project creator. My experience is that, to showcase a retro game is best at getting people's attention. A snake-game would be fun. I actually have developed one for a similar events years ago, but the source code is not at hand. However, I can definitely make you one in 2-3 days. Do a simple search in google for "snake game" and you'll know what I'm talking about. I hope I can help you on this one.