Basic Rules

What You Need to Play:

If you are playing with the starter deck, you need the two 12-card decks, two sets of 20 strategy cards, one 20-sided die, 1 playmat, 1 rules sheet, 1 rules card included in the starter set.
Number of Players: 2. One for each side. This should be rather obvious, but just in case anyone wondered, here it is.
Game Length: 25 to 60 minutes, depending on how long you have been playing, the rules you use, and how many innings the game lasts.

General concept of the game:

Two players play out the nine innings of a Major League Baseball game with teams from the starter deck.
A "team" consists of at least nine "players" that fill in all of the field positions and at least two "pitchers" with a 20-card strategy deck.
Your goal is to score more runs than your opponent does in nine innings.

Getting Started.

Open up the playmat and look at the layout, familiarizing yourself with the locations of all the cards during play. Lay the player cards on the playmat in their respective places, in whatever order you choose, and the pitchers in the bullpen. Your strategy deck goes to the left of the first batter.
Your starting hand size is three. You can have as many cards in hand as you want.
Each player draws a card at the beginning of each half inning, including the top of the first (in other
words, every time there is a switch between offense and defense).

Play the Game.

Player one puts forward the batter, and player two puts his or her pitcher in the middle of the field.

Step 1: The Pitch!

The pitcher's player rolls the 20-sided die and adds the die roll to the Control of the pitcher.
If the result is greater then the On-Base value of the hitter, then the pitcher made a good pitch.
If the result is less than or equal to the On-Base value of the hitter, the pitcher made a bad pitch (for him at least).

Step 2: The Swing!

The player on offense then rolls the 20-sided die to see the results. If the pitch was good (die + Control is greater than hitter's On-Base), look for the results on the pitcher's chart in the lower right-hand corner of the card.
If the pitch was bad, then look for the swing result on the batter's chart.
If the batter gets on base, move his card to the appropriate base. If the batter makes an "out," put the card back in the player's lineup spot and flip the card over to help you remember that the player is out. If the offensive team gets three "outs," the pitcher's team comes up to bat.
Once both teams have made three outs, the inning is over and the original hitting team continues with the next player from the lineup.

The Strategy Cards.

Offensive (red) and Defensive (blue) cards can be used when you are on the offense or the defense, respectively. The cards tell you when you can play them and what they do to affect the game.
Utility Cards can be played when you are on either defense or offense. As above, the cards tell you when you can use them and how they affect the game.