Take ALL of your fancy features and put them aside. Take ALL of your necessary features and put 90% of it aside. Take the entire world and put 99% of it aside.
Reduce the entire project into a MVP, down to a tiny map with almost no features and make it work.
Once it works, start adding in based on this criteria:
A: Must be included, ie. almost nothing.
B: Should be included, but can be sacrificed.
C: Would be included if possible.
Once category A is done, you move items from category B into category A. You then free up space in B and start sliding C items into B.
If I was doing this, I would let the players vote on category B upgrades and eventually category C upgrades. This can also be a great PR strategy, because if the product is aimed at satisfying the player base, they will tell others. If you dismiss the player base, they will also tell others. In the beginning though, having non-biased players to keep you accountable on category A is vital. That means, don’t believe everything your friends and family tell you, because they are biased to making you feel good. Non-biased players are biased towards making themselves feel good, which will result in more honest feedback. Not to forget that the majority of your player base, if this succeeds, will be strangers from the Internet, most of whom you will never actually communicate with personally. If they like this game, they will tell others, if they don’t like the game, the studio or the dev team spokes person, ie. you, they will also tell others.
By getting people to play the not-so-great demos packaged regularly along the way, you will get hints on what should be focused on and what can wait.
The game doesn’t have to become spectacular in one year, it just has to be fun to play and with little to no errors and bugs, keeping the VIP fans engaged during the development time. Once the first version is launched, it will have to be fixed and maintained. After that, regular updates and upgrades can bring the grand vision to reality.