Gym Manager is a game where you get to manage, build, and expand your own gym, in opposition to the gym where you were previously employed. After being fired by the gym owner, you decided to get revenge and spend all your savings on opening a new gym, with the goal of making your former boss bankrupt.

As the main mechanic of the game, you will have to manage, build, and expand your gym. You can buy new equipment, upgrade existing ones and sell supplements. You can also expand your gym by demolishing walls, buying new decorations, and opening facilities like a sauna, massage salon, solarium, and locker room. Meanwhile, you must protect your gym from potential danger, keep the gym clean and manage your members.

Outside of managing your gym, you can engage in various activities in town, including flirting with girls, sabotaging the competition gym, partying, buying cheaper equipment in a second-hand store, doing illegal business with a shady guy in the backstreet and lockpicking and stealing from the town while avoiding the police.