While Kosnett's Imperium article is largely about economics and tactics, a brief description of how the game is played is in order. The following text is condensed from the Imperium rules.

Sequence of Play:

The game is divided into two identical player-turns. During each player-turn, the moving player conducts maintenance and production, then executes the first of his two movement phases. After the first movement phase, the enemy player is allowed to move a limited number of his units in reaction movement. Following this reaction phase, the moving player executes his final movement phase. Combat takes place directly following each movement phase.

Movement:

There are two methods of movement: sublight and hyperspace. Sublight movement is slow, allowing the moving ships to move only one hex per game-turn. Hyperspace jumps are limited to the jump routes printed on the board, but ships can make an unlimited number of jumps per turn, stopping only when they enter a hex containing enemy units.

Combat:

All fighting takes place in three segments - space combat, surface to space interdiction, and surface combat. During space combat, enemy ships pair off in one-to-one combats; extra ships can remain outside of the battle or can double up against enemy ships. Each ship fires once, using its beam or missile factor depending on the range. The range is determined at the beginning of each combat round; each player rolls a die, and the player with the higher number selects the range. The player with the smaller fleet adds one to his die roll.

During the space to surface interaction phase, ships in orbit may bombard units on the planetary surface, attempt to land while carrying ground units, or drop jump troopers. Certain units on the surface can attack the ships in orbit. Finally, in the surface combat phase, enemy units on the planet surface attack each other.

Economics:

Each player receives a certain number of Resource Units (RU's) to pay for maintenance and the construction of new units. All starships located in a system containing a friendly world marker require maintenance costs equivalent to their maintenance number. Remaining RU's may be spent on the construction of new ships, which will be completed on following turns.

More Tactics in Imperium

Sci-Fi Strategy
Player's Notes
Monitors: Imperial vs. Terran