Tip for making a video game. put constraints on yourself, it makes your creativity work extra hard (sound cringe but it true) also don't try to add a million things, A good moto to follow is that every piece of content will double your work time even if it does not seem like it, for example: power sliding, now you have to make sure nothing is conflicting ,add more animation ,make sure it feels right and etc.
its an awesome thing to have big views and ambitions but its better to know ones limits and work from their. Also bringing in more people is a good idea, but remember if you don't pay them don´t be surprised if they feel like they want to leave or change things about your original vision for the project.
PS, Good luck!