Decide what potential pvp looks like and how it will be moderated very early on. Some people can do it but competition can and will bring out the worst in some people.

Keep the group small to start to give yourself time to get used to modding. Run an interest check and keep in mind that plenty of people can be encouraging but not actually app. If you want to make it private, consider whether you have enough reach to pull in a sustainable population.

Have a pitch that's a bit more direct than what you posted here, because "themes of" doesn't tell people as much about what the game is meant to be as something like "this is a zombie horror survival game set in the ruins of city x, where characters wake up from a coma with no idea how they got there and have to band together to survive" would. Also, figure out what will distinguish your game visually and play-wise from other horror and horror adjacent games, and make sure you lean into that.