The 'Mech Duel Rules, also colloquially known as the "Solaris Rules", are a set of 'Mech combat game rules from the boxed set, Solaris VII: The Game World.
The 'Mech Duel Rules simulate battle between BattleMechs (or designated ArenaMechs) on a much higher detail level than the standard BattleTech boardgame rules do, to which they are very similar otherwise. In a way, they can be said to break up standard game turns and scales by a factor of four, requiring micromanagement of what is covered in a single turn's actions under standard rules.
The most important changes are as follows:
- A turn represents 2.5 seconds of real time (as opposed to 10 in the standard rules)
- The scale is four times smaller than the scale of the standard rules, changing the diameter the area a hex represents from 30 meters down to 7.5 meters and quadrupling weapon ranges accordingly.
- Weapons produce four times the heat of their standard values, creating heat spikes even where none could exist in the standard game the heat scale is adapted to this; heat sinks operate during each turn to match
- Most weapons require some time to recycle until they can be fired again, measured in rounds.
- Because of the limited time, a MechWarrior can perform only a certain number of actions per turn (e.g. walk, fire a single weapon, fire a Target Interlock Circuit, etc.)
- There are some advanced actions like evading, aiming or sprinting.
- A jump can last up to four turns and it is possible to change the course or to fire during a jump
The higher level of detail offers more tactical options but the game gets more complex and time consuming as well. Consequently, it is typically only suitable for fights between very small numbers of combatants (usually 1 on 1).
Because of the modified heat recording system and the limitation on fewer actions per turn, players must consider their moves carefully. They have to decide when the time is right to fire, as the 'Mechs run a lot hotter and the respective weapons may not be used in the following turn(s). In addition, the scale shift and quadrupling of the weapon ranges (in game hexes) ensures that weapons with a long minimum range, such as LRMs which have a minimum range of 24 hexes under these rules, are difficult to use reasonably.
Together, this leads to a distinctively different performance of some weapons and of whole BattleMech designs. Many designs that shine in one rule set perform poorly in the other.