One thing I dislike is rules that encourage a big free-for-all in the middle, or a bland, linear battle.
The Boring Gun Line
One thing that's always put me off about Napoleonics (besides the amount of painting and rather bland units) is the gun-line that stretches across the board. This is often even more marked in Ancients. Both sides arrange their forces in neat lines, advance to the middle, then roll dice until usually one flank collapses and the army gets rolled up. Realistic or not, it's simply not that interesting to me from a gameplay point of view. But that pales in comparison to:
The Massive Scrum
That Firestorm Armada game where everyone parks in the middle and chugs dice until one side blows up. That skirmish or platoon game where everyone converges on the single building. Any Warmachine game, where everyone is clumped within a 12" radius. These situations usually degenerate into who goes first, who activates the best special ability, or (more likely) who gets lucky with the dice.
Admittedly some eras and genres are easier to include maneuver. Dropzone Commander does it well, with airmobile troops within fast APCs able to be dropped behind enemy lines or directly on distant objectives. Infinity's ability to use stealth, airdrops, and to chain activations can see units break dynamically through enemy lines.
But how can we avoid that "big clump in the middle?" How can be encourage units to maneuver in an interesting way? How can we make it worthwhile for units to consider spacing out? Concentrating your forces is a good tactic, but when both sides do it, it can be boring. How can we tempt players to split forces, flank, and hold different areas of the board? How can we give players the opportunity to create mismatches rather than piling their balanced 1500 point armies into a single evenly matched melee?
I don't think there's a single answer, but here's some factors that can move games away from "everyone stacks on."
Large terrain pieces break up "gun lines" and give opportunities for flanking or holding against superior numbers. A favourite tactic of mine in LOTR was to divide my force into small chunks (i.e. 3+ or so groups of 5-10) and offer one of these little groups temptingly to my opponent near a prominent terrain piece. They would usually break their force into maybe two bigger chunks of say 15, each outnumbering my small groups. I'd use the terrain to hold across a small frontage (or in the case of goblins, climb up on it/over it) against his superior numbers, then combine the rest of my small groups into a large group (20+) to outnumber/squish the other half of his army, then proceed to link up with my small "forlorn hope" defensive unit which was by then often using "defensive stance" to survive. Terrain makes many tactical opportunities for those willing to divide their forces.
Command & Control
This usually encourages tightly knit forces, but should not mandate it. I like the games where working with a leader is beneficial but not compulsory. I.e. units clumped up around a leader may get a bonus to activation or +1 to morale, but there are drawbacks too - i.e. an easier target. Units should not be penalized too severely from being detached from the main body. "Unhistorical!"
Not necessarily. It's not like a squad leader is incapable of moving his squad unless he is within 20 metres of his lieutenant. Detaching units or parts thereof and fighting independently might by slightly disadvantageous, but it should not be impossible, and it should even be advantageous to (gasp!) split your forces at times.
Activation - get rid of IGOUGO. This mechanic allows players to perfectly order their attacks and formations without realistic interference, and makes it easy to group forces for orderly, concentrated attacks. An alternate move allows an opponent to take advantage of a unit that is out of position. A reaction system allows a unit to be held up by suppressive fire or a unit to counter-charge unexpectedly. A card based system can create randomness to be exploited.
Unit Formations should give different, distinct benefits. Like the difference between a skirmish line and fire-by-rank; one
offers better survivability, the other more concentrated firepower. Spacing and formation of units should give subtle benefits and drawbacks, so you are encouraged to adopt different tactical stances. In bigger battles, I like to offer a "withdrawn" unit or flank - a gap enemies can rush into, or use skirmishers to pull units out of position. Do the rules allow this? The rules need to make disrupting an enemy possible, and perhaps occur organically i.e. a wild warband making a compulsory charge when an enemy is in range.
These rules are rare enough in some genres (like sci fi or moderns) that when I see them I tend to raise my eyebrows. I'd say being outflanked is as relevant to a WW2 squad as it is a horde of medieval peasants. No one likes attacks coming in from all directions, and by encouraging units to occupy flanking positions we encourage said units to maneuver away from the main body. It's similar for directional shields on starships - if shields can be boosted on a particular side, it might encourage co-ordinated attacks by ships split up to approach from different directions.
I'm using these in space games, having been inspired by their use in EvE Online. There's nothing like a big nova bomb template to encourage ships to spread out. Artillery and magic can likewise put a damper on concentrated forces. Automatic weapons (like MG42s) can act in a similar method with a teardrop or template to force enemies to spread out or split up. I'd even consider using a template for unit firing (Battlefield Evolution for example allowed squads to attack anyone within 6" of a designated target figure - so while spreading your own unit out could make some minis immune from attack, it could also take them out of gun range themselves when the time came to retaliate).
Scenarios & Missions
I can't stress this enough. If the mission is "kill them all" every time then a "death blob" may be the fastest way to do it. However simply adding objectives to hold does not always fix the problem. Most of the time, the guy who spreads his forces to hold the objective gets his smaller groups stomped by the guy who concentrated his into a blob. I mean, it's easy to capture objectives when your opponent's army is completely destroyed. Accruing VPs for each turn an objective is held, or imposing a time limit can sometimes help prevent this but I don't have a magic bullet here, except note that scenarios need to be designed during the game design process, and not added as an afterthought.
Again, over to the readers. What are some good ways to prevent units clumping up into a "deathblob" in the middle of the table? How can we encourage units to maneuver?
It kinda comes down to risk vs reward. If trying interesting maneuvers is all risk and no reward - becomes the game rewards tight clumping or offers no potential reward in maenuvering forces - then players will be trained not to take risks.
If making rules, a good question to ask yourself - is there any reason in this game for a player not to push all his minis into the middle and simply slug it out? What benefits are there to maneuvering?