Ken Griffey Jr.'s Slugfest is a baseball game for the Nintendo 64 and Game Boy Color, featuring real-life player Ken Griffey Jr. It was released in 1999.

The batting feature in this game is set up differently from most other baseball video games. The batter is given an elongated oval shape to control and in order for the batter to make contact with the ball, he must wait for the pitch location and then move the oval to the location of the pitch to make contact. Each batter will have a different sized oval or hitting zone depending on how strong of a hitter he is. This feature was originally developed in Major League Baseball Featuring Ken Griffey Jr. and carried over into this game with slight modifications.

The fielding portion of this game makes use of the c-directional pad on the Nintendo 64 controller. As a fielder, you must run to the ball using the analog stick and then choose the correct c-button for the base to which you would like to throw. The controller has four c-buttons: c-up, c-left, c-right, and c-down and each of these represent a different base. Each c-button represents the base that would correspond with its location on the controller. For example, c-right represents first base, c-up represents second base, c-left represents third base, and c-down represents home plate.