I have to disagree, minefields are actually extremely inexpensive. As a force multiplier their cost is drastically lower than the cost of say a tank. When you look at the finances behind defending a large tract of land, a division of armor is much more expensive than a few thousand mines. More importantly they allow for economy of force. If you have 2/3 avenues of approach covered by mines then you only have to dedicate forces to defending the 3rd avenue of approach, and maintain rapid response capability to the other 2. As far as minefield maintenance, there's virtually none. Sure you have to go out and replace mines that have been destroyed by the enemy, but you don't go out there and perform maintenance on each individual mine. That's why they are so appealing to field commanders. Also, I think the fact that there are non-profit organizations around the globe still trying to clean up minefields 20-50 years old is proof of this. While in the military I handled Claymores and PDMs, both are extremely easy to use, inexpensive and can be left out for indefinite amounts of time thru all weather. For a few decades now we've had the ability to deploy mines via airdrops and artillery, they are in effect the easiest weapon to use in our arsenal. Back to civ though, Camikaze is right about the scale of Civilization. 1 square represents a huge amount of land. However 1 square can also be defended by 1 mechanized infantry unit, so unless they increase the depth of maps in Civ 5 we'll just have to suspend reality as we often must with the Civ series. He is also right about minefield spamming, which is why there must be negative consequences for deploying large amounts of mines. 1) The tile they are deployed on would not be work-able until an engineer (or worker) expends a very long amount of time to remove them. 2)That tile would also hinder allied movement speed, ending any extra movements to friendly units that enter it just like it would to enemy units. 3) It would also give friendly units stuck inside it the same attack and defense penalties enemy units would have (you can't maneuver well in a minefield). 4) Minefields would hinder cultural borders. Nobody wants to be part of a civilization that creates huge fields of these terrible weapons, and cultural expansion represents new peoples wanting to be part of your civ. They can either hinder the closest friendly cities cultural output or just 'freeze' your borders in x amount of squares radius around the fields. Positively though they would also halt a nation's borders from expanding to the squares the fields occupy. Yes this could be seen as an exploit since you could box other civilizations in, but see the next point first... 5) Minefields would cause unhappiness in the closest friendly city they are built to. This is to represent the population's revilement of mines as a weapon. That unhappiness would scale exponentially as more fields are deployed, since more images of children with stumps for limbs would be beamed to their televisions. 6) Negative political relations. Pretty self-explanatory I think. This could be coupled with a UN ban or limitation on minefields. This would go hand-in-hand with an improved and more in-depth diplomacy system. The pros would include: 1) causing % damage to all units that enter a minefield until the mines are 'expended'. The amount of units a field could damage would be relevant to the amount of time spent deploying, tech level and enemy counter-mine actions. To combat mines units could have promotions (or if they include a unit customizer like they should in civ 5, customized ability) that increase a unit's mine degradation abilities (their ability to degrade a field's strength) 2) halt cultural border expansion (albeit at the unhappiness cost) 3) units caught inside a field suffer penalties to attack and defense To counter minefields enemies would: 1) bombard a minefield with artillery (DCM's ranged bombardment) to decrease it's strength, or bomb it for the same effect. 2) use diplomatic pressure to get you to stop or remove your minefields, much like in the real world. Yes minefields would be spamable, but doing so would be at great cost to your diplomatic relations and happiness levels in cities. However like I said before, the current transportation methods in Civ would have to be drastically re-thought in order for minefields to be a viable addition to the game. Transportation avenues and fortified positions must have a greater tactical weight to them. In real life mines are used to deny avenues of approach and to funnel the enemy through desired lanes of fire. This would be extremely difficult to represent in Civ, thus making mines a less viable addition to the game. One option may be to bring back zones of control to units (my memory is a bit foggy, this is from Civ 3 right?), this is just a thought though.