period of a few hundred cycles. According to Crawford in Chris Crawford on Game Design, the system starts with a basic "plan" and then applies any available cycles to trying variations on that plan, selecting higher-valued outcomes. A few thousand cycles are available between each VBI, so given a typical order-entry phase of a minute, the computer has millions of cycles to spend on refining its plan. The AI is based on three basic measures of the game state: The strategic situation which attempts to take and hold cities, the tactical situation which attempts to block player movements, and the overall arrangement of the front line. The AI first attempts to build a continuous front line in an attempt to prevent encirclements, it then sends additional units on intercept courses to block player movements, and finally any remaining units are sent to undefended cities. As Germany, the player begins with more-mobile units, shorter supply lines, and concentrated forces. Although the AI is not strong—believing that the computer needed help against a human, Crawford intentionally did not fix a bug that benefits the Russian side—the computer has greater numbers, much more territory, and winter weather. Because of iterative pondering, the computer's moves become better the longer the player waits before issuing orders each turn, and a tactic that works well in one game might be less effective in another. The computer's larger forces allow it to put up a credible defense; direct fights are hopeless for the player, as newly arriving Soviet units eventually overwhelm the German forces. Crawford spent much time tuning the arrival times of new units to balance the gameplay, and warned that a player who attempted to overwhelm the Russians with tanks is "guaranteed to lose. What you are supposed to do is maneuver, encircle, demoralize, and defeat". The manual advises using blitzkrieg: Use mobile armored units to break through and encircle Russian units, and infantry units to eliminate enemy pockets. According to Crawford, Eastern Front is an example of a game with a sharp jump in the learning curve; "apparently there is just one trick in the game, mastery of which guarantees mastery of the game". While he did not specify the trick, there are ways to trick the AI. One is to break the German forces into two blocks, and then advance them on alternate turns. The tactical part of the AI attempts to intercept