From the back of the box (US edition):
"Raw Power At The Plate
Batter Up knocks you deep into the world of championship baseball - with hard-hitting action, screaming line drives, impossible diving catches, and sizzling pitches. Jump to snag hard-to-reach fly balls. Snake thunder fastballs past the batter!
In Password Play, you'll captain your team through a championship series. You control the lineup! Call in pinch hitters and relief pitchers. Bunt or steal a base.
Choose from fourteen teams, two stadiums, plus games lengths of five or nine innings. And take advantage of two-player mode to create your own world series with a friend."
User Description: Baseball game developed by Namco for the Game Gear, and released in Japan and North America. The game is similar to Namco's earlier Family Stadium games in presentation and gameplay. Choose from 14 teams: 12 representing Japanese professional teams, and 2 All-Star teams.