Leave the leader boards out of the main game. If you add them in, make them an optional add-on. Look at MineCraft -- Players can play single player, or they can join a multiplayer online game. MC is also an example of how successful a game can be even without fancy graphics and interfaces; It is a low poly voxel game, and has a minimalist UI.
Focus your energies on the game engine and mechanics first. And research how to gain market and exposure. Just having a "great game" will not bring in players who have no idea it even exists. Some of the best (IMO) designed games still failed miserably because a lack of marketing, and are rarely mentioned or heard of anymore. Yet, some really mediocre games are talked about and played by millions world-wide because their marketing places them constantly in view of players. If players hear a game mentioned enough, they get curious and play it.
You have it here on Itch, now get it on Steam and Good Old Games (gog). Possibly start a Patreon, and/or a Discord. Actively seek out player feedback, comments, suggestions, etc. And always be thankful for any such -- If someone comments "I sucks!", reply with "Thank you for your feedback! I/We want to improve the game! Can you tell me/us why you think it sucks, and/or what I/we can do to make it better?" If nothing else, people like to be heard, and know they have been heard.
(Edit to add: Try to make it multi-platform, as well. I use Linux, not Windows or Macintosh, so I cannot even try the game.)