We're all familiar with "I go-you go" rules: one side activates all of their units, sometimes in whatever order they want, and then the other player goes. Obviously, this is far from realistic in the way it reduces the battle to two large men taking turns punching each other as hard as they can until one falls over. It can be plenty fun of course, (as in All Quiet on the Marian Front) but most tactically-minded folks seem to eventually prefer something more interesting when they can get it. For convenience sake, I'll even include games like Wings of Glory (or Battletech), where both sides actually act at the same moment (and to a degree even X-Wing, where pilot skill determines the order of activation), as both sides essentially get the same chance to act, and all intact units can do whatever their abilities allow every turn. I've actually seen CWC described as I go-You go, as one side takes as many activations as possible and then the other does, but as there is a limiting factor to the activations, I prefer to think of it differently.
The other two types I've lumped together are "negative" and "positive" limited activation rules. Both are an attempt to improve over the "I go-you go" type by limiting what you can do in a given turn. These rules recognize that you can't always coordinate everything on a battlefield perfectly, and limits the units activated on any given turn. This strikes some as less fair, but of course, there is often the same chance of activation on both sides, and if there is a disparity, most rule sets give some kind of benefit to level things a bit. I'm of the opinion that limitations like this are desirable in most cases, but there are two very different ways to achieve it.
"Negative Activation" - So, say you want to move or shoot with a tank or something. In negative activation, you try to activate, usually with a roll, and sometimes you can do what you want with the unit, and sometimes the dice say "nope, your tank is going to sit right where it is and spin its treads." A good example of this is Cold War Commander, where you can activate a unit over and over on your turn, until you fail your roll. That failure can happen on the first, or on the sixth activation, you never know. I've had games where a tank company's commander fails to activate for entire game, forcing the overall commander to activate the company and move it to the fight, all while the inactive command unit is literally sitting at the table edge as the rest of his unit reaches the other side of the board. So much for "simulation". Lion Rampant (which seem to be quite popular lately) uses these rules as well, and I've seen some griping about it online which makes me suspect I should find a different rule set if I dive into a medieval setting.
Positive activation works differently, limiting you by using mechanisms like cards or dice that are drawn either for each unit, or determine the order of activations during a phase. Examples of this type are Bolt Action, where both sides have a die per unit all in one bag, and one die is drawn to see who goes next (allowing the possibility of one side going several times in a row), but leaving the choice of which unit to activate with that die, and with the knowledge that all units will eventually activate. Similarly, in IABSM, the units form a deck of cards, and you activate the unit which you draw, but may not get to activate every unit on a given turn (there's a "tea break" card that ends the turn somewhere in the deck). Or, as in my current favorite rule set, Chain of Command, you roll a set number of dice (typically 5) that you can then use to activate various units depending on the numbers rolled. You roll the five dice, and within certain limits, make the best of what you have. If you have lots of units, you may not be able to activate them every time, but once you roll the dice, you'll at least know for sure what you can do. Sometimes, if you roll lots of sixes and fives, you can't activate as many things, but you either get several turns in a row (6s) or advance towards a CoC die and the various tactical options that brings. You may not be able to do much, but you won't be stuck doing nothing either.
I also feel this is a huge improvement over Bolt Action, as once you roll you know you can, say, activate a squad, a junior leader, and a team, and thus you can have your units support each other in a way that is impossible (except by blind luck) in BA. For instance, given the above roll, I could activate a tank's driver as a team, telling it to advance on the road, while activating a squad's junior leader to follow the tank closely, using it as cover. Try that in Bolt Action, and if you draw one of your opponent's dice after moving the tank, they will find your squad still 20' back from the infantry in the open until you can pull another dice to move them. There's no way to do two things simultaneously. Yet I still prefer Bolt Action's "positive" activation to CWC's "negative".
To me, what makes the positive activation superior is that the activation method limits your resources, and then allows you make your choice of how to work with limited options. I call the former negative because it allows you to make your choices and then limits you by sometimes saying "no". I find the latter to be psychologically less fun, and leading to far more annoyance. Perhaps others agree, perhaps not. But for me, this feeling of positive choice, of being able to make a plan to work with what you have (even if limited), is far more fun than trying to stretch your brain to explain why one of your tanks is still sitting on the table edge watching the rest of the battalion get torn apart. If that tank is sitting there, I want that to have either been a conscious decision, either because I wanted it there or because I chose to spend my resources elsewhere.
I guess what this comes down to is that I don't like being told "no" arbitrarily. Tell me what I can do, not what I can't, and I'll happily try my best to solve the tactical problem at hand, and enjoy myself win or lose. I don't mind being denied, but I'd ultimately prefer it be my opponent, and not the rules, which do so.
Another issue I have with CWC is the way it handles reactive (opportunity) fire. I admit to limited experience with this mechanic in games outside CWC and perhaps CoC, but I've seen others gripe about this online so I know I'm not alone here. Essentially, in CWC, any unit that is not "suppressed" by previous enemy fire, may interrupt an opponent's action and fire in reaction. Frankly, I'm not as clear about why this doesn't work well in this game as I am about the activations. I can only give you the result: paralysis on the game board. It may be because every unsuppressed unit can do this. Certainly in CoC you have to spend precious tactical resources to do it, whether by putting a unit on overwatch, or spending a CoC die on an interrupt or ambush. In CWC, it again feels more "negative". Certainly some kind of mechanic like this makes sense - if I'm moving my tanks into a better position, you probably do have an opportunity to fire while I do so. Yet, you could do so if I remained passively right where I was - but not in CWC. I can just hang out where I am ("if I don't move they can't see me"), you can't shoot at me, at least not until your turn. And if you do fire on your turn, I can use reactive fire to fire back then. In the end I find the way the mechanic plays out limits options too much and drags the game down.
What I DO like about CWC:
I do like the combined arms focus. Planes, choppers, artillery... these are well done and appropriately deadly and chaotic. Admittedly, I bomb my own troops WAY more than is statistically likely, but I've laughed every time, because even that is kind of fun. If only the rest of the game was a bit more fluid on the table, and a little less arbitrary and frustrating. I also like the rules for botches - double ones force a roll on a very fun "bad things happen" chart.
So Cold War Commander, adios. Michael is accommodating me, and we'll be trying Fist Full of TOWs next for our 6mm Cold War games. I'm hoping it work out better, and I have a feeling it will.