I don't think anything was decided. It's all still wide open.
There's something to be said for starting with a game-in-development "donated" by one of the contributors. It would allow us to hit the ground running, not spend weeks or months hashing out a basic design before people could start working on graphics, dialogue, code, etc. Also, starting from something fairly well defined might keep everyone focused, instead of going off in all kinds of incompatible directions.
SSH is obviously a talented guy, and I think his proposal deserves serious consideration. From what I have been able to gather about
Awakening of the Sphinx, I think there are a few points that speak against this particular game for use by the project, though: 1) It's set in ancient Egypt, the most over-used adventure game setting there is. 2) It seems to aim for historical accuracy (or at least plausibility), which would require a lot of research by the people who would want to get involved. 3) It deals with politics and religion, which can be sensitive subjects. I'm all for controversial games, but I think a project like this should try to be as inclusive as possible.
As for your proposal, bspeers, I first of all think it's great that you're making one. It gets the ball rolling, so to speak. I don't agree with everything you say, though. Specifically, I'm not sure a comedy adventure is the way to go. Sure, the game could be funny, but making an implicit promise to be funny is very risky. Few things are more painful than jokes that fall flat. Also, I worry that a "humorous" label will be taken as a license to throw in all kinds of "wacky" ideas. Your summary does not reassure me. Finally, it sounds a bit derivative of
Day of the Tentacle?
Maybe I'm all wrong, and one or both of the above ideas would work great for the project. In any case, I'll put up my own proposal for you all to consider:
I propose that we make a game that is ... adventurous!
What I mean is to aim for the atmosphere of those children's cartoons from the eighties (when most of us were kids) where a group of people (kids, mostly) are looking for something, and have to travel through many strange lands and deal with many tough situations on the way.
People from the UK will probably remember
Mysterious Cities of Gold:

If you're from France, Norway, or a handful of other countries scattered across the world, you may know
Les Mondes Engloutis (aka
Spartakus and the Sun Beneath the Sea, aka
Arkadia, aka
Shagma):

Americans will most likely first think of the animated
Dungeons & Dragons series:

(I'm not saying the game would necessarily look anything like these pictures.)
Often in these shows, each episode would have the characters travel to a new land or city, with a different culture and people. They would have to deal with a dangerous or challenging situation, and then be on their way (apparently not any closer to their ultimate goal). There was usually a recurring antagonist, some villain who kept following them and making trouble. That kind of episodic format seems like it would work well for a project like this.
It could go a little something like this: It's pretty far into the future, on Earth or some alien planet. Things are quite primitive, so it's difficult to travel, and people know very little of the world outside of their own local area. In a small city-state, the Queen lies dying. When she is dead, her cousin the evil Duke will take the throne. However, the Queen's young handmaid overhears the Duke mention that the Queen secretely had a daughter, somewhere in a foreign land. She resolves to set out to find the heir before the Queen passes away. She is joined by several companions (more by chance than anything). However, one of the Duke's agents is following them, determined to stop them, or kill the heir to the throne before they can locate her. Their search will take them far and wide across a strange world they hardly know, teach them unexpected things about themselves, and reveal a far bigger secret than who should inherit the throne.
It's rough, but it's purposefully rough. The entire plot is essentially a macguffin, a relatively arbitrary motivation to keep the characters going. We could all work on revising it and filling in the blanks. What do you think?