What would you consider a working prototype?

Hey folks,

I wanted to raise this question out to the community. For a long form RPG (think at least 12hr+ play time), how far along in development would you feel you’d need to before presenting your work as a working prototype for a grant? Would you feel like you’d need to have all the mechanics worked out, skill trees, save and load, battle mechanics, etc…? All the stages built out? All the script written out? Or is it enough to have the basic mechanics and a working, blocked out stage? At what stage should the character designs/modeling/animations be?

There is probably no definitive answer bit here is my take.

You should have at least samples of all the main systems, especially what is unique about them.

For an RPG I would have a sample area, including some battles. A pair of classes with limited skill trees. The prototype is meant to prove, to yourselves as well as others, that your ideas work in practice and that you are capable of realizing them.

If possible, a vertical slice of the game is great. It shows a complete but short part of the game. It conveys “this is how it will be, but much longer/bigger”.

For someone who evaluate the prototype, it should be a concept that has been developed, which is not a concept anymore.
Which shows that what you saying is not just an idea or a concept, but you have an ability to make it to an actual product.