With an eye to giving people something fun they can use to punch up one of their old board games, I have decided to post some variant rules I developed for the Castle Risk version of the Risk game many years ago (sometime in the early '90s, as evidenced by the perforated-edged paper that I used to run through my word processor back in those days). They are just as useful today as they were then, of course, and can also spark ideas amongst readers for their own variant rules for this or other games. They include rules covering Fortifications and special characteristics for the six nations that appear in the game. As usual, I have made tweaks and edits throughout for clarity. 

Fortifications

There are three custom Fortification counters that can be brought into play during the game and allow a player to build a fortress on any territory he or she occupies, accomplished by returning four Marshall cards to the discard pile. A Fortification will remain where it is placed until such time as it might be destroyed. As with a Castle, attacks against a Fortification are never made with more than two dice; possession of a Fortification, however, does not grant more spoils. Furthermore, if the Fortification is captured then the new owner can either use it themselves or opt to destroy it at the end of any of their turns. If a Fortification is destroyed, the counter is removed and can then be used again. [

Initially I had specified that there were three custom Fortification cards that should be inserted into the deck and might be drawn from it. This proved to be somewhat unsatisfactory, however, as the homemade cards for Fortification and other things stood out from the official manufactured ones and everyone present thus knew that one of these was being drawn.

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Empire Unique Characteristics

Each of the six empires in 

Castle Risk

 has unique characteristics that can be reflected in the game. This is accomplished by having a pair of custom tiles or large cards for each empire that are given to the player whose castle is in the respective area at the beginning of the game. These can add color to the game and help give the various empires individual flavor. 

The tiles may be played up to once per game each when appropriate, in conjunction with another card or specified condition, and may remain in effect under certain conditions are met. When one of these empire-specific tiles is played in conjunction with another card the effects described on the tile prevail over those listed on the regular card. For example, when the Russian Winter card is played in conjunction with a Marshall card both are discarded, but the regular Marshall effects are not applied. In no case is a player constrained to use one of these custom tiles and does so solely at their discretion. 

Initially I allowed some of the custom tile effects to function once per game and others to function two or more times each but eventually decided that it was easier to keep them balanced if I simply allowed them to each function once and to then have fairly coequal effects. Each of the nations have a type of elite units associated with them and the French Imperial Guard, Ottoman Janissaries, and Russian Cossack Horde all function identically for rules purposes. German Uhlans initially functioned the same as these other cards but for variety — and because Uhlans never historically played as significant a role in the armies of Germany as the units associated with the other powers — I changed them to function mechanically like the Austrian Jaegers, while the British Fleet is unique among the elite sorts of units available. I had also originally written up the Ottoman "Revolt" tile so that it functioned mechanically much like one of the other types of troops callups, triggered by Reinforcements or Hidden Armies. This did not seem very satisfying, however, and I decided that keying it to the use of Diplomat cards and viewing them as agitating mullahs was more appropriate and interesting. 

+ Austrian Empire +

Diplomacy Minister: Played in conjunction with a Diplomat card, once per game the Diplomacy Minister can force a Treaty between Austria and another power at any point, even after an enemy has announced or begun an attack. The Treaty must, of course, also be honored by the Austrians. Duration is through one turn of the person it was played against and one turn of the Austrian player (just as with a normal Diplomat card). 

Jaegers: Once per game, a body of Jaegers can be called up in conjunction with a Reinforcement card or Hidden armies. Jaegers receive +1 to their highest die roll when attacking to or from an Austrian territory and +1 to their highest die roll when defending an Austrian territory. If desired, these units can be used to replace non-Jaeger armies in Austrian territories, and those replaced regular units can then be placed on any territories held by the player outside of the Austrian Empire. 

+ British Empire +

Lord High Admiral: Once per game the British player can use this tile in conjunction with an Admiral card. When in play, the Lord High Admiral causes naval attacks to be more effective than usual and to receive +1 to their high die rolls. Like a normal Admiral, the Lord High Admiral remains in play and can even be used from turn-to-turn until such time as he is killed. 

Fleet: This tile is activated by the playing of a Reinforcements card or the calling up of Hidden Armies (which are in this case applied to the Fleet rather than whatever territory the player designated). These armies are placed on the fleet tile, which is thereafter treated like a territory and can have additional armies placed on it from new Reinforcements or Spoils. If all the armies on the fleet are eliminated at any point then the Fleet is destroyed and its tile removed for the remainder of the game. The Fleet can be used to attack enemy coastal territories and has advantages over the use of an Admiral, namely that is can cease attacking if the player wishes and that the player does not have to move all of its armies onto the conquered territory if it wins. The Fleet can also be used  to intercept attacks against territories within the British Empire (but no those outside it held by the same player). In this case, the Fleet is placed next to the attacking Admiral card and the battle played out. The Fleet can withdraw from the battle at any point but the attacking forces do not have have this option. If the attacking forces win the battle or drive off the Fleet then they must follow through with their announced attack. A player can also use an Admiral for purposes of attacking a Fleet and, if successful, any surviving armies are simply returned to the territory from which they originated.  

+ French Empire +

Emperor: Played in conjunction with a General card, the Emperor will will add +1 to the two highest dice when the French player is attacking. Like a normal General, the Emperor remains in play and can even be used from turn-to-turn until such time as he is defeated. If both the dice are beaten by the defender, however, the Emperor is removed from the remainder of the game. The Emperor's bonus cannot be applied to attacks that require the use of an Admiral, nor can they be used when the French player is defending. 

Imperial Guard: Once per game the French player may form an elite unit of Imperial Guardsmen, placing them on a single territory. This must be done in conjunction with a Reinforcement card or with the revealing of Hidden Armies, either of which will dictate the size of the Imperial Guard force. Any attack such troops participate in will be at +1 to the highest die. Players must keep track of how many armies are lost from the force, starting with Imperial Guard units, and when a number equal to the number of Imperial Guardsmen in play is gone the +1 bonus ceases. Reflect this by using armies of another color, special counters (e.g., pennies, miniatures), or by keeping the Imperial Guard units on the custom tile (which will not remain possible if the guard force gets divided into two or more groups). 

+ German Empire +

Field Marshall: This tile is must be played in conjunction with both a General and a Marshall card. It will thereafter add +1 to the two high die rolls both when attacking and defending, until such time as the Field Marshall is defeated and removed from play. 

Uhlans: Once per game, the German player can call up a body of Uhlans in conjunction with a Reinforcement card or Hidden armies. Uhlans receive +1 to their highest die roll when attacking to or from a German territory and +1 to their highest die roll when defending a German territory. If desired, these units can be used to replace non-Jaeger armies in German territories, and those replaced regular units can then be placed on any territories held by the player outside of the German Empire. 

+ Ottoman Empire +

Janissaries: Once per game the Ottoman player may call upon a corps of highly disciplined Janissary shock troops, placing them on a single territory. This must be done in conjunction with a Reinforcement card or with the revealing of Hidden Armies, either of which will dictate the size of the Janissary force. Any attack such troops participate in will be at +1 to the highest die. Players must keep track of how many armies the attacker loses, starting with Janissary units, and when a number equal to the number of Janissary in play is gone the +1 bonus ceases. Reflect this by using armies of another color, special counters (e.g., pennies, miniatures), or by keeping the Janissary units on the custom tile (which will not remain possible if the Janissary corps gets divided into two or more groups). 

Revolt: By playing one or more Diplomat cards, the Ottoman player can incite a revolt by Muslim locals in any enemy-occupied territory in the Ottoman Empire, or in any enemy-occupied territory in the Austrian or Russian empires bordering the Ottoman Empire. The number of armies created by the revolt is two per Diplomat card played. These armies must then fight those occupying the territory, with the victor gaining control of it. 

+ Russian Empire +

Cossack Horde: Once per game the Russian player may call upon a horde of Cossack cavalrymen, placing them on a single territory. This must be done in conjunction with a Reinforcement card or with the revealing of Hidden Armies, either of which will dictate the size of the Cossack force. Any attack such troops participate in will be at +1 to the highest die. Players must keep track of how many armies the attacker loses, starting with Cossack units, and when a number equal to the number of Cossacks in play is gone the +1 bonus ceases. Reflect this by using armies of another color, special counters (e.g., pennies, miniatures), or by keeping the Cossack units on the custom tile (which will not remain possible if the Cossack horde gets divided into two or more groups). [Tile should show mounted, charging Cossacks with sabers overhead.] 

Russian Winter: Played in conjunction with a Marshall card up to once per game. In each battle of the subsequent attack, the attacker will lost 1 army, in addition to the normal results of the battle and both sides might thus lose armies regardless of the results of the dice rolls. Once this tile is played in response to an attack the attack cannot be called off until it is either won or the attacker has only 1 army left (and it is possible that the attacker might be left with no units in the territory from which it attacked).