It seems like there are two ideas about gravity vehicle going around. One idea was that the car would be propelled by a falling mass, presumably pulling a string to turn the wheels. But other sources say like an eggless scrambler. From my kowledge of scramblers, they were pushed by a swinging mass of some kind, but then just coasted. So which is more accurate? Does the power source travel with the car? Just so I can begin to conceptualize some plans.
The second one is closer, but still not quite there. It will be a vehicle travelling down a ramp, propelled solely by its own mass.
Please tell me you are kidding. Everybody has to build ramps? No pulleys, hammers, or springs? Why? Why force everybody into the same cramped shoebox?
I am very, very disappointed.
Ramp design and construction will be a critical part of the competition. While it may seem very basic, ramp geometry (flat vs. curved and if curved, what shape exactly), material selection (friction, strength and weight will all be considered by top teams), transportation issues (the ramps may be difficult to move, requiring rapid disassembly/reassembly) and the launching/release mechanism all add significant complexity to the event. All of those factors will have to be optimized for you to consider doing well at a state tournament or nationals.
In my mind, one of the key benefits of this event is that it will be very accessible to brand new teams without direction while also offering many factors for optimization. Reducing mechanical complexity does not necessarily mean an event is more "simple," just easier to visualize.
I do not see it as a cramped shoebox at all. By your assumptions, forcing everyone to use mousetraps as the propulsion method for a vehicle is equally cramped. There will be a tremendous amount of variation between teams throughout the year.