One of the issues that has arisen a number of times over the years has been stacking and supply. As to supply, there are no supply requirements for military units. They can trapse across the known (and unknown) world and suffer no effects from being thousands of miles from their home Country . Seriously unrealistic and detracting from the playability of the game. As too stacking, any Civ player with any experience has faced the "Stack of Doom" with 80 some odd units stacked in a single tile bearing down on a single hapless City. This effect is not only unrealistic - it is down right depressing fro ma playablity perspective. I have even suffered a Stack of Doom from a Country of only three Cities which never should have been allowed to accumulate so many units - such a small Country should not have been allowed to support them. I play tested war games (board and computer for several decades some time ago and decided to apply that experience to dining a solution for these two issues for Civ. War games usually have very complex rules concerning supply but very simple rules concerning stacking. To address the issue of supply, I used the general rule that any older units that were not gun powder units (i.e., allowed to be built in the Ancient/Classical/Medieval Eras) could essentially live off the land - as they did in the real world. The primary problem with supply was transportation - getting the supplies to the troops. Once the Renaissance Era was reached, I created a new unit that was a Horse Supply Unit. It had a movement factor of two but essentially no defense strength (like workers/settlers). The supply range of a Horse Supply Unit was 8 tiles from the nearest friendly border. Friendly units who were up to 8 tiles away from the (and stacked with a Horse Supply Unit would be deemed in supply (Horse Supply Units could not provide supply to Armor/Mechanized/Motorized units). For units that were built after the discover of the Automobile, I created a new Motorized Supply Unit with a movement factor of three and also no defense strength. Friendly units who were up to 12 tiles away from the nearest friendly border were (and stacked with a Motorized Supply Unit) would be deemed in supply. If a Supply Unit was lost or separated from the stack, that stack was automatically considered out of supply and suffered the consequences - being that any unit that was out of supply had their movement factors reduced by one and their combat factors halved (rounded up). Supply routes could not be traced across lake or mountain or desert hexes. Any units that captured a hostile City were automatically deemed back in supply if the captured City was not blockaded and a route could be traced back to a friendly coastal City. All Scout/Recon/Commando units were exempt from any supply requirements. All Paratrooper units were automatically in supply for two turns. To address the issue of stacking, after much experimentation, I arrived at the following limits for each stack of units in a tile: 10x line units (warrior/spear/sword/musket/rifle/infantry/motorized infantry/mechanized infantry), 4x mobile assault units (cavalry/armor/modern armor), 4x siege/artillery units (ram/catapult/bombard/cannon/artillery/motorized artillery/mechanized artillery), 4x support units (AT/SAM), 2x recon units (Scout/Explorer). This general rule took away the problem of the "Stack of Doom" but still allowed large attacks by forcing the players/AIs to use multiple tiles. Much more realistic As related in a concurrent post, for the last several years I have play tested a number of my suggestions (including the additional food/commerce/culture and negative culture) for approximately 40 games. I used World Builder to implement each game change for each turn (for me as a player and for the AIs), which became quite tedious at times. However, the work paid off in the long run. I had no AI problems (although the changes had not been programmed in but were manually inserted each turn) but much more important was that the game became more playable and realistic and much more interesting with no added significant frustration (or cursing at the game) because of the impossibility of stopping a "Stack of Doom" or helplessly watching a stack of hostile units unrealistically run rampant through the countryside destroying your carefully and lovingly built empire even though they realistically should not have been able to do so without supply. Testing was easy - I did so with voluntary limits I used World Builder to chop AI "Stacks of Doom" down to size and move them back when they exceeded their supply range It was tedious but the testing was successful Stack limits can be easily implemented (in the same way that certain units are forbidden from entering certain tiles - instead of a terrain limit place a number limit on the units allowed in enter the tile. Supply limits are also easy because an AI algorithm could be made that simply observes whether a unit would be out of supply if it entered a tile and not implement such a move. If a Supply Unit was lost, the AI could then decide to either return to friendly borders or bring up another available Supply Unit. Thoughts anyone?