Wagering game system and method with session RTP adjusted based on player skill

A gaming machine and method include a monetary input device, a user interface configured to: enable a player to select a wager for a game of chance having a skill-based activity, to interact with the game of chance using a gaming input device. A processor is programmed to enable the player to win a prize based at least in part on input from the gaming input device, and to set at least one parameter of the skill-based activity or the gaming input device to a first difficulty for winning the prize during a first game of a gaming session including a plurality of games, and to adjust the parameter to modify the difficulty to a second difficulty for winning the prize during a subsequent game of the gaming session to maintain a predetermined percentage or percentage range of money or credits returned to the player (RTP) during the gaming session.