The first question is where and how you plan to get your $500k budget, and the first-first question (because really you should have an idea before spending $500k) is how do you plan to make it back, and then some?
A seasoned programmer probably expects in the neighborhood of $100k/year salary, give or take $20k, with benefits like healthcare and 401k on top of that. plus there's equipment and facilities if you plan to work in a central location. All told, $150k/year for a developer is about right at the lower end. You can probably pick up a reasonably bright recent graduate or someone with maybe one game under their belt for maybe $70k-$75k salary, so call it $100k all-told. That's half your budget.
For another $200k, or perhaps a bit more, you can probably find 1 seasoned artist a promising artist who's recent grads or wanting to break into the industry, and a level designer. That's 90% of your budget, at least.
Whatever's left can probably buy you a decent soundtrack, foley, voice-recording, and a reasonable level of production on those, if you don't need a ton of individual pieces. That's all of your budget.
That doesn't include a marketing budget, or any budget for project management, game design, or marketing, or any pay for yourself whatever role you intend to play. It bought you about a year's worth of burn time to get your project done, or at least to a stage where you can seek additional funding.
That's just one example configuration that I think would be reasonable.
I don't think the coding would be that much work, especially if you used an engine like Unity. You could probably get by with just one programmer if they are seasoned and well-rounded. They might cost a more per head, but less than a senior programmer + one that's more-junior. It might free up enough for another level designer, a project manager, or some marketing.
But at any rate, it sounds vaguely like you're lining up several carts in front of one very and increasingly anxious horse. If you're seriously considering financing this somehow, you should really develop the design more fully, do some market analysis, project sales, and build out a prototype on a much smaller budget.
Of course, all of that is the route of throwing money at it to make it happen. If you can succeed at selling your vision, this kind of project is not beyond accomplishing with a few years time from some dedicated hobbyists. Easier said than done, of course, but possible.
