Combat game question

Okay, so I have a team verse team combat game (similar to generic roleplay gaem) that I’ve been working on for about a year, I’ve been polishing, and it’s looking good so far. But the only problem, I do not know how to keep players in game as its centered around combat, and that can’t happen because theres no other people in-game. I was wondering what to add, or what I can do to keep the players in so the actual combat part happens. I have a few ideas, such as the game being confusing, as to why players leave, but yeah. The objective of the game is to save your team from being plunged into starvation. Thoughts?