Lots of good ideas in this thread. Let me throw my 2 cents in as well. I spent 5 years writing R&D proposals to government agencies related to educational/serious game development, training simulations, health technology, and VR. Projects that were funded, I managed and acted as lead designer/developer. One thing to keep in mind is that in my case I was proposing an idea that I wanted funded so that my company could do the work. I'm not sure your situation is that you are seeking funding or you have money and are seeking a team. Regardless of your situation, the actual proposal is going to look pretty similar.
So, on to the important things to include in your proposal.
0: If you are sharing a proposal with other individual or private entities, get a mutual-NDA signed before sending over ANYTHING that details your idea. If you don't, you will have little, and possibly even no, legal recourse if they steal your idea. You can go to rocket lawyer and for 5 bucks, get a NDA drafted. If you are dealing with an established organization, they will probably have a lawyer that can draw up an NDA too. Get this in place ASAP.
1: What is the problem or issue that your idea is going to solve? Whether you are proposing an entertainment product, piece of art, or serious application, you are ultimately trying to solve a problem. It could be figuring out a new interaction mechanism for VR, exploring VR as an emerging art form, or making it easier for people to see what VR is like - there is something there that your idea is aiming to address. Make sure the person reading your proposal understands not only the problem, but also why the existing solutions do not work well enough. If you are building a game, why do we need another Type-X game with hints of game-Y?
2: What is your solution to this problem/issue? Imagine you are presenting an onion to someone. There are many layers to this onion, and you will eventually explain each layer. But to start, explain the outer most layer. What will your solution do? How will it be used? Why should it be built? Why is your idea the one that will solve the problem? This is your chance to sell your idea as one of the ways to solve the problem. Try to keep this section brief - 2-3 paragraphs, some bullet points, maybe a concept figure.
3: Ok, I'm interested, what do you think is needed to build it? If you have done your job of selling your idea as a solution to the problem, and the reader agrees that the problem is worth solving, then they'll want to know about what you think actually needs to get done. What are the high level tasks? How long do you think it should take to build a first version? What are the risks associated with the tasks? This is your chance to start peeling back the layers of the onion. If you are trying to hire a development team, this would detail the specific tasks and work that team should work on. Quick tangent, I've done contract work for other companies, as an individual contractor and as a sub-contractor at my R&D job, and the absolute worst thing is when the entity you are working for does not give very clear tasks and expectations of should be done.
4. We can build it, but will it sell? Congrats! You have a prototype / MVP. But did the market you just built this product for want it? What indications are there that this work was actually worth pursuing. Tying shoes as a kid is hard - we have a problem! - and someone could probably spend a fortune building a robot to automate shoe-tying - we have a solution!. But would anyone actually buy this shoe-tying robot instead of spending 5 minutes watching a youtube video? This section is probably more important when you are writing a proposal that is asking for money, as your investors want to know it won't go to waste.
Anyway, feel free to PM me if you have questions, or want someone to review your proposal draft.
Just a simple idea. One thats cheap but helps with immersion in windy weather. Allow bluetooth fans to activate according to the flow of wind upon the player. People can place them anywhere they want and they can be cheap to make and cheap to buy. The setup can just be "use fan 1 as front fan, use fan 2 as front left and so on." People should be allowed to put them in any order they want and i feel like this doesn't need more explanations.