European Chess is Machiavellian Chaturanga for Four, using different armies. There is another description, somewhat different, here. I am very glad that the authors have found my set of variant chess pieces so helpful.
The game is held in high regard. This applet is very much under development. I welcome suggestions.
Take over an opponent's army by capturing the last royal unit. In the official rules of European Chess, there is no check, though the computer player(s) will generally avoid allowing their armies being lost in this way. Alex Nisnevich, inventor and publisher, explained to me:
In European Chess, after much playtesting, we finally decided that one takes over an army simply by capturing a king. There is no check or checkmate, and so you do not have to move your king out of check. (This can be used diplomatically in many ways, for instance to pressure another player to sacrifice a piece to save your king.)
If a player has only one unit remaining, the army disappears.
Since I realized that playing an applet does not involved much of the diplomacy that exists when real human being play, I also have programmed European Chess With Checks, where an army is obligated to escape check if possible, though this does not override a Belgian treaty.
In European Chess With Lightning, armies change whenever a unit captures or is captured by conventional means.
In European Chess With Flags, is won by getting another army's banner to one's own corner square. I haven't got a good machine strategy yet. Sorry.
In European Chess -- King of the Hill, victory is attained by maintaining a presence on the four central squares. Again, I don't have a good machine strategy yet.
Americans on each turn after the first have a 1/3 chance of being allowed to choose any other nation's special ability, and an additional 1/3 chance of having one assigned. America must not be in checkmate / stalemate. Only some nations are available. Americans cannot choose those with special pieces (Carthage, Egypt, Fire Giants, Greeks, Gupta, Inca, Ironclad, Sparta, Tartarus), special histories (Ancient China, Canada, France, Germany, Nuclear Rogue, Switzerland, Turks), abilities that cause unanticipatable catastrophe to others (Iraq, United Nations), or secrets (Old Soviets, Vietnam). Choosing Athens, Austria, German Holy Roman Empire or Japan requires the requisite units. Choosing Britain allows the American royal pieces to move as knights. Choosing Russia renders America immune to the Russian winter and speeds it. Poles are under development. This is an alteration of the actual game rules but I thought it made sense.
Ancient China has a wall through which runners cannot move. This should block pushes by Revolutionary France and the Gauls, and the Prussian pull. I decided that passing the edge of the wall stops diagonal movers.
Armenians can make two non-capturing moves with a unit that starts within two orthogonal moves of the patriarch. The patriarch is royal, non-capturing, and a K / B / 2,2 leaper.
Athens has bishops (ships) that can move to any empty space as often as once every other turn. However, no bishop can move this way to attack an opposing royal unit. I disallowed attacking any British minister because of the common theme of democracy.
Atlantis can sink or raise squares, making them un-passable to non-royalty that have other moves.
Austrians capture a unit already under attack by one of their knights by attacking it with a second knight.
Aztecs can transform rooks into knights, and knights into rooks.
Balkans can attempt to assassinate an opposing unit in the home quadrant.
Barbarians after capturing an enemy cannot be recaptured until they move or three turns elapse, but cannot move unless a friendly neighbor is within two squares.
Belgians after capture of a unit can invoke treaty rights to require another player to capture a unit of the capturer in turn, if possible.
British have four kings that also move as knights.
Byzantine units can return to unoccupied home squares. If an army has been taken over, pawns return to squares of their original sides, other pieces to Byzantine squares.
Canadians can restore two captured friendly units to play over the course of the game.
Carthage has elephants that move up to 3 squares as rooks, and can only be captured by units within 2 squares (measure orthogonally.)
China can censor a non-royal piece, forbidding it to move, provided the army has more than three units. I did not allow this to work on second moves by Armenian, HRE, Japanese or Viking units.
Colonists can set up militias, moving like kings, capturing only 1,1 and unable to leave the home 3x5 area.
Cossacks can move bishops and rooks as knights.
Crete turns the central sixteen squares into a labyrinth that scrambles opposing units. I programmed so that pieces may be randomly displaced by only one square in whatever orthogonal or diagonal direction. This is the older version; the newer version, in which the player has some choice, isn't manageable here because a player can click a unit, see where it would go in the labyrinth, and then choose a different piece.
Crusaders ("kings of Jerusalem") place one non-royal unit that has not just moved in a castle where it can only be captured by royal units.
Dutch after the first move can switch identities when a non-royal Dutch piece moves orthogonally alongside an opposing non-royal unit.
Egyptians cannot be captured by opponent special powers, and pharaoh can 2,2 leap.
Fellowship (of the Ring) wins if the ring-bearer pawn promotes. If the ring-bearer is captured, lose a piece, or the game if only a pawn is available. Whoever captures the ring-bearer can take and extra move or take the ring for its own.
Fire Giants can use the power of Muspelheim wielded by their leader, once, to destroy everything in an area.
French can hold a revolution. After guillotining the king and two pawns, the rook becomes an immobilizing, N-moving orator, the knight becomes an orthogonal pusher of non-royal units up to three squares orthogonally, and I didn't implement the change for the constitutional bishop. The last non-pawn is royal. I decided that units held immobile by the orator could not give check.
Germans (Holy Roman Empire) can move two different castles on one turn, though not in the same direction. A castle cannot capture an opponent who has just captured a German castle.
Gauls can push an opposing piece of the same type two squares away, or only one if the second is blocked. Pushing off the board destroys the unit.
Germany can move a group of orthogonally connected units to a congruent group of empty squares.
Greeks ("Mycenae") can load, unload, or burn the Trojan horse. I did not allow more than one king into an individual horse, and no burning horses containing a king. I need to add the ability to let a second unit per turn in/out of the horses.
Gupta Empire uses archers with a range of six orthogonal units, not shooting over another unit.
Gypsies do not have a king and do not promote pawns.
Huns can can drop a pawn within one square of the usual starting area every other round instead of moving.
Hurons can ambush from behind another piece as if to an adjacent square.
Incas send diplomats to recruit opposing units.
India has inights able to move as 2,2 or 2,0 leapers. The last knight is royal.
Iraq has a king, knight, and bishop that destroy any non-royal unit horizontally or vertically adjacent to them at the start of the player's turn.
Ironclad is immune to capture by a non-royal unit, but does not attack royal units.
Isengard pawns make noncapturing moves one square orthogonally in any direction, capturing moves one square diagonally in any direction. Wormtongue cannot capture an opposing royal unit but if he gives check, the opposing side cannot capture an Isengard unit for four turns or while Wormtongue remains on the board. Saruman is royal, and moves as K+N+R.
Israelis follow each move by placing a barricade that cannot be entered or crossed by a non-royal unit.
Italians have bishops that can also jump 2,2; after reaching an opposing corner, they can also jump 2,0.
Japanese rooks, bishops, and knights, when no other side is the only one of its kind on the board, may move twice. Rather than forbid this if the first move ends in a check, I simply did not allow a second move to capture a royal unit (or any British magistrate.)
Macedonians can retire any number units to gain an additional turn each, but checking ends this.
Mafia bishops and rooks move a maximum of three spaces. Captures are made without moving the capturing piece.
Mayas develop their units' abilities over time.
Mongol pawns move one empty square orthogonally or capture one empty square diagonally in any direction, promoting on either far rank to any standard piece.
Mordor king Sauron is royal 2,0 or 2,2 leaper. The witch-king moves as a knight. Add a pawn every turn so long as the witch-king survives. No promoting to witch-king. At least every other move must be a pawn move. The haradrim (rhino) moves 1 or 2 squares orthogonally, destroying a leaped opposing unit. It may only be captured by a unit within 2 squares orthogonally.
North Korea periodically develops insanity. I took the rules to require that each insane piece make a single move. If North Korea is the only human player, the backup key restores the board to the last time that North Korea was sane.
Nuclear Rogue can destroy one opposing pawn, knight, bishop, or rook once every five turns, beginning on the fifth. The count returns to zero if any unit of the nuclear army is captured.
Old Soviets conceal which one of their units is royal. This is from the older rules. The updated rules, which which recall Toilet Roll Chess, were too difficult for me to program. Sorry!
Orcs replaces lost pawns. This is the old-style Mordor.
Pala Empire has unusual piece movements.
Persians whenever checked can swap the king with a friendly unit.
Picts bishops and rooks can leap 2 or 3 squares, but no on two successive turns. They cannot be moved by other units' special abilities.
Poles offer a pawn to an opponent for a non-aggression pact. The Poles cannot capture for 4 turns. The other player cannot capture for 2 turns, then if a capture is made, the Polish army get an extra pawn.
Police taser (immobilize) any unit under attack by a non-pawn. Only police kings and pawns can capture.
Portuguese can move, but not capture, as if edges were connected.
Prussians have the options of pulling all units orthogonally within 3 squares toward them.
Romans can move two pawns in a single move.
Russians as per the newer rules, so long as there is a Russian player, all non-Russian, non-royal units die of cold after two rounds with no orthogonal or diagonal neighbor.
Saladin uses chivalry points to prevent being attacked.
Spanish add a pawn adjacent to the king each time that an enemy unit captured.
Spartans have a unit that moves as queen-plus-knight and is not subject to special captures, pushes or pulls.
Swedes can move both king and a non-royal unit, as often as every other turn.
Swiss non-royal units cannot be captured by an opponent who has not taken or lost three or more units, is not in check, and has not lost a unit to the Swiss army.
Tartarus has a chance to return units as ghosts, and its king is not royal.
Terrorists select a unit to carry a bomb to blow up all orthogonally and diagnoally adjacent units.
Trenches pawns promote on the sixth rank. Maximum of one queen.
Turks enter their units on the board from a reserve.
UN Peacekeepers: Pawns move as kings. Bishops and rooks move a maximum of three squares. After you move, any opponent adjacent to one of your pieces and unable to move is captured. If this is a royal unit, the royal unit vanishes and you own the rest of the army. No capturing or being captured except within home territory. If three of the same opponent are in UN home territory, that opponent takes over the UN army.
Venice: On every other turn, the Venetian naval blockade can suppress an opposing army's powers until Venice's next turn. British magistrates lose the ability to move as knights. The ringbearer does not win immediately by reaching the end rank, but does win as soon as the disability is removed. If any army that is suppressed has a Spartan warrior, that warrior loses its invulnerability. Gypsy pawns move as normal pawns but still do not promote. Greeks may not enter, leave, or burn a horse. Carthage and Pala elephants can be captured from any distance. The Soviet king becomes royal, and the secret royal unit remains so. UN peacekeepers lose their invulnerability to normal capture and their ability to remove adjacent immobile units, but do not gain the ability to capture normally. Powers return if Venice is destroyed or if the power is required to enable escape checkmate or stalemate.
Vietnam can lay traps that destroy those moving to the square and delay those crossing it. I decided that if a unit is moved into a trap by the Gauls or the Prussians or the French Revoltion, it is destroyed, but that if merely passes over there is no effect. According to the new rules, there are a maximum of five traps and a new one cannot be placed while an old one is in effect.
Vikings can move a rook twice so long as it does not check or capture.
The outer space and rewrite history contest entries are praiseworthy but would take up too much programming room, at least for now. After adding the third-contest entries Cossacks and Hurons, I'm out of programming room. Thanks for understanding.
These are simple illustrations rather than strong opponents.