I firmly believe that it would a great idea to add Multiplayer to the game so Players will be able to spend more time and have more fun while playing your game. In that way, many people will buy your game as it may become popular if streamers notice that multiplayer Co-op is added (especially that period of time while Epic Games provided the game for free + gamers spend more time searching for new games during the quarantine). I hope you take into account my opinion as this matter prevented me to buy your game (me and some friends). (- Also during the year 2021 games should have multiplayer options )
Thank you for your time,
An optimistic gamer.