My current version of the Sword of Terra rules are based on rolling 1d10, adding a modifier, and comparing against a value. For example, when making an attack with a direct fire weapon, a player rolls 1d10 and adds the weapon’s accuracy modifier before comparing against the other unit’s target number. In a few cases, such as initiative, opposed rolls are used where each player rolls 1d10 and adds a modifier with the highest roll winning.
The game is divided into rounds, each of which has several phases. Every unit has the opportunity to act during each phase in order to let the rules model every unit’s actions taking place simultaneously.
At the beginning of each round, the players roll an opposed roll modified by their Command Rating in order to determine the initiative order for the rest of the round. The player with the highest roll moves last during each phase in order to allow them to better react to enemy actions.
During the Movement Phase, players first take turns moving their units. Then once all units have moved (or declared that they are remaining stationary), any active missile salvos move in a straight line towards their targets.
During the Attack Phase, players declare their weapon attacks. After all units have fired their weapons, missile salvos that reached their targets make damage rolls.
During the last phase of each round, players check to see if they have achieved their victory conditions. If no one has won the engagement, then the game continues with the next round’s Initiative Phase.
Each ship has several statistics that determine its capabilities in Sword of Terra.
A ship’s Target Number determines how difficult it is to hit with direct fire weapons. In order to hit a ship, the attacker must make a roll of a weapon’s Accuracy against the Target Number of the ship.
A ship’s Armor Ratings determine how resilient it is to weapon hits. Each ship has three Armor Ratings: fore, side, and aft. When a ship is hit by a weapon, the attacker must make a roll of the weapon’s Power against the ship’s appropriate Armor Rating in order to cause damage.
A ship loses one (or more) of its Hull Points each time it is damaged. When it has no remaining Hull Points, a ship is destroyed and removed from the game.
A ship’s Threshold is the number of Hull Points that it can lose before it starts to take damage to other systems by means of Damage Effects.
Thrust represents how quickly a ship can move and maneuver. Each point of Thrust allows a ship to move one inch forward, and Thrust is also used to make turns.
A ship’s Turning Cost is the amount of Thrust used for a turn of up to 90 degrees in either direction.
Turning Distance is the minimum number of inches that a ship needs to move in a straight line between turns.