Muscle Clicker is a click-tap incremental game with an exercise and weight-lifting theme. The player's goal is to direct a super skinny character to improve their muscle mass through exercises with dumbbells, an exercise bike and competitions.
The player can customize their experience. Along the top of the screen, they use a yellow icon marked with a figure to change the character's gender, the color and style of their hair and clothes, and their strength and stamina. They collect and store purchased items via the green inventory icon marked with a handheld weight. They buy equipment and stimulants via the red store icon marked with a brown bag. They turn off the sound, adjust the music, and select a different background with the blue settings icon marked with a gear.
The game allows up to three music track selections. With the background, the player can select a bedroom, a beach, a room with a window view of a forest, or a lunar room with rocks and stars and galaxies decorating the walls.
Muscle Clicker rewards the player with experience and money. The player tracks their progress and stamina with two horizontal bars. They can review their current funds from rewards and competitive events below the second bar. To the right of the character, the player can select the mode of exercise using the two top vertical icons (free weights or an exercise bike) and the competitions (pullups and squats) with the lower two icons.