A system, a machine-readable storage medium storing instructions, and a computer-implemented method are described herein for a System Tuner for customizing a player's experience. The System Tuner calculates a player skill level for a player. The System Tuner modifies at least one attribute of a second game level based on the player skill level prior to game play of the player in the second game level. The System Tuner detects game play of the player in the second game level. The System Tuner identifies a difference between a current rate of progression of the player and a reference rate of progression. The System Tuner triggers the modified attribute of the second game according to an extent of the difference between the current rate of progression and the reference rate of progression.