Having said so much about what you don't have to be able to do, here's what you will need to make something like FC:
- An idea. It doesn't have to be entirely or at all
original, it just has to get people to consider looking at the thing. This is the easy part.
- The ability to start working on something intimidating. You probably can't stand up a playable game without learning how to do a few new things. You don't have to do them well, necessarily, just enough to make something that someone else sees value in.
- The ability to keep working on something that overwhelms you. This basically means doing the same stuff you'd do to stave off momentary panic and medium-term depression/anxiety. Take walks, talk through the problem with someone, adjust your posture to be neither slouched nor clenched, take your meds if applicable.
- The ability to keep working on something that bores you. This is the flip side of the above, and much of the same stuff applies. There's a magical happy medium zone where something is just difficult enough to be *fun*, and no meaningfully-sized project will park within this zone. Sometimes no particular tactical change is needed and you just need to accept the boredom and commit to doing the work. Other times no amount of this will work because you're barking down the wrong tree.
- A willingness to do everything yourself if you have to. A swarm of autists will not build your game from nothing for you. They will extend and improve a game they love, but you'll have to get it there, and it will almost certainly take longer than you think. People, especially the kind who would be most useful to you, can smell when you need them and they don't need you at all.
- A willingness to publish your work. If nobody sees it, you will know, and you will almost certainly stop caring. Something every day is ideal. Something every week is pretty much necessary.
- As much as you hope to use the work of others, the ability to manage them. I don't know how much this can be taught or even described, but the basic idea is that you need to make it so that other people both can and want to do things the project needs.
All but the first of these are generic life skills you can acquire with practice, unless you're a complete genetic clusterfuck, which you're probably not. Making anything big enough requires you to have your shit together in rough proportion to the size of the project. Remember to start with a small part of your idea instead of trying to set up the whole thing at once. Take a look at the first playable build of FC if it's not clear how small I'm talking.