First up was a session of Hold The Line, the Worthington Games title that uses the Clash For A Continent system, itself a descendent of Richard Borg's Command and Colors system. Unlike C&C, HtL does not use cards nor even a division of the map into the flanks and center. Instead, a special die is used that produces rolls of 1, 2, or 3 (in equal measure) and this number is added to a scenario-specific number of Action Points (AP) that each player may use during their turn. In some cases, as in the Hobkirk's Hill scenario that we played, one side may even that that number altered - the Americans treated a "3" result as a "0", so were essentially hobbled an action per turn in addition to their one-smaller base value of 2 (the Brits got at least 3 AP per turn, so that was a two AP advantage on average for the Brits).
There are no plastic units or blocks, but rather very heavy stock counters that have a printed "morale value" (or, as referred to copiously in the rules, "MP", which is unfortunate as in the vast majority of wargames that means movement points). Instead of removing a unit, you simply flip a unit to show the weaker side, replace an already flipped unit with a replacement units of lower value, or remove it altogether if the unit is at it's lowest morale. In addition, unlike in any of the C&C games, morale actually has a use besides in determining how brittle a unit has become - it's used to determine if units retreat when being close assaulted (an expensive but very effective form of combat).
Perhaps the largest rule change is that of rally. A leader stacked with a unit can, for one AP and neither unit moving for the entire turn, restore a single MP to that unit. The effect of this rule is that you almost certainly want to pull back units for regrouping even when they've only lost one or two MP, and that units are only going to die if they are the subject of intense fire.
The other thing that HtL adds to the table is a timer for one or both sides. In our scenario, the Brits had 20 turns to get 6 VP from taking my VP spaces or eliminating my units. If I was able to cause 6 VP in casualties before that happened, or if the Brits didn't have 6 VP by the end of turn 20, the Americans would win.
We played using the advanced leader rule (they may be able to take more hits, and can give extra dice in close combat but are also much more likely to die). My Americans start on a line of hills with two leaders, an arty unit, four or so militia cowering behind the hill should they be needed, and a single dragoon who's only purpose so far as I can tell is to dart out and kill a weak unit at a critical time. In my case, I used the dragoon immediately and lost it for a single step loss in return.
Since this was our first game, Matt's Brits, starting out in a clump to one side of the American line, tried to flank the line, but he was leery of the American arty and didn't make an assault until the very end of the game which resulted in destroying his fifth unit but not taking any VP spaces. I, on the other hand, who had no reason to do anything but sit there and wait for the Brits to advance because of the time limit, thought I'd try out assault tactics but got roundly spanked for my efforts (and helped Matt get to 5 American losses by game end as a result). It became very clear that those two extra AP per turn for the Brits more than offset the burden of attack, as I could be expected to get 3 AP on average to his 5, or only 60% of his AP over the course of the game.
The game is clearly in the C&C mold, with a very simple system, a fair amount of chaos (although I felt the AP system was better than the standard C&C card-based system as you weren't forced to let critical units sit - even during the ARW, units would protect themselves if fired on or assaulted), balanced by quick playing time, rewards for playing in a historically accurate manner (to a point), and a good number of scenarios. Matt assured me that Clash for a Continent had somewhat different rules, although the systems of war hadn't evolved much in the 12 years or so between the Seven Years War and the American Revolution. I haven't played that earlier title, so I can't say.
As such, HtL is a bit of an odd duck for me. I feel like C&C: Ancients (by quite a margin my favorite of these titles up to this point) does a better job of simulating the warfare of the period (I would think that close assault should inflict casualties on both sides in HtL, especially because it's so bloody, but there is no Battle Back rule as in Ancients), but while I like what some of the action cards do in Ancients I do like that you have more flexibility in your operations. Communications in and of themselves hadn't changed much - you still sent runners with orders to a sub-commander - although command structures had improved a bit. Flintlocks and rifles and artillery are clearly more useful at range than the javelins and arrows of the earlier era. I'm not sure if I prefer the dice method of Ancients (you need certain symbols to show up on the various dice) as opposed to HtL (you just need to roll "in range").
Plus, of course, with Ancients you get to put all of those stickers on all of those blocks (I actually enjoy this, much as I enjoy clipping counters), but setup is a pain and with three expansions I now need six different Plano boxes to hold them all (Roman 1, Roman 2, Macedonia, Carthage, Persia, Barbarians). It would be much easier to stick expansions to HtL into the base box as the cardboard units just go in baggies.
All in all I think I'll see where the series goes from here in terms of innovation. Fortunately, I have room for both series (although I suspect Battlelore is going to go on the block soon for a variety of reasons), so only time will tell. If you don't own a C&C game but were thinking of taking the plunge, I think that you are best served by choosing the milieu you find most appealing - if you like elephants charging across a field only to stomp your own units (and who doesn't), then Ancients may be for you. If you're a fan of the Age of Reason and the ARW, Hold the Line may be your ticket. Otherwise, I'd recommend playing both games before making a decision.