High Heat Major League Baseball 2003 is based closely on the previous year's version, with all the same game modes and options, some changes in graphics and some other additions.

All previous game modes return: Exhibition, Season (16, 81 or 162 games), Playoffs, Home Run Derby and Practice. Season progress is again saved to battery-backed RAM. Multiplayer has been added with two-player matchups via link cable. Teams, players and stats have been updated for the new MLB season.

Gameplay is also largely unchanged. Batting and pitching are again done from a view behind the batter, but with the batter now rendered in real-time via polygons. The pitching interface via the pitching cursor is unchanged, as are the isometric field graphics. Some advanced playing techniques have been added: it is now possible to steal bases and throw bean balls.