Since I may be the only person on these Forums that has actually handled and fired a matchlock musket, I've got to put in my two pence' worth.
And no, I'm not (quite) that old, but I went to a Feld Day of the Sealed Knot Society, the English Civil War Re-enactment group in England, and when they found out I was an active duty soldier they (this was back in the 1980s) talked me through loading and firing one of their muskets.
First, the Musketman as a separate melee unit is a Fantasy Unit. A man with a matchlock musket or arquebus has NO Melee Factor - he's carrying a 15 - 20 pound (7 - 9 kilogram) clumsy club which, if he's smart, he will throw away as soon as the enemy reaches him so that he can either draw his sword or run like Hell. In most cases historically, his sword was a cheap little 'hanger' and he had almost no training with it, so running away was the preferred option if available. To stand and fight against real swordsmen or pikemen was, simply, suicidal.
That means that almost as soon as the first adequate individual should-fired firearm became available (1470 - 1472 CE, shoulder stock added to the 'hackbus' or Hook Gun, making it practicable to fire the gun without a wall to rest it on) they were combined with other troops that had a Melee Factor:
1486 CE - Emperor Maximilian of the Holy Roman Empire forms the first Landsknechts, combining pikes, two-handed swords, crossbows and arguebuses
1493 CE - 'Colunelas' are formed in Spain, the 'columns' combining pike, arquebus, swordsmen and halbardiers. A few years later when they started putting three Colunelas together permanently, they became
Tercios.
In other words, Pike and Shot units develop out of Musketman Units in about 2 - 4 turns, and after that there are no separate Musketman units on an open battlefield. Other 'expedients' to keep musketmen alive were:
1526 CE: Ottoman
Janisseries use multi-rank volley fire with muskets at the Battle of Mohacs - deep formations and trained swordsmen protecting the muskets while they reloaded to fire another volley.
1545 - 1550 CE: Ivan the Mighty equips his
Streltsi with long 'berdische' axes as hand weapons in addition to their muskets (arquebuses). As it happened, the curved inside of the axe blade also made a convenient musket-rest for firing.
Battle of Nagashino, 1575 CE: The Musketmen were protected by wooden palisades so they could load and fire volleys undisturbed by enemy cavalry charges. BUT the Musketmen did not even attempt to engage in Melee - that was left to the rest of the army.
And, finally, the modern formation and drill techniques that made the Tercio and its ilk effectively obsolete, in 1592 CE Maurice of Nassau drew up the Dutch Army for review by Battalion - a permanent linear unit (6 ranks deep) of 1/3 pikes to 2/3 muskets which could both defend against enemy cavalry and infantry with the pikes and shoot any deeper formation to bits with volleys of musketry. In the 1620s CE the Swedes under Gustaphus Adolphus added light artillery to that mix in the Swedish Squadron formation that was the first true Combined Arms unit in modern history.
How to depict all this in the Game?
First and foremost, the Musketman, if you insist on keeping it, is a Ranged Unit with a 1-Tile range and a minimal Melee Factor. Since at about the same time (1460 - 1490 CE) the Field Artillery with long barrels, trunnions and trailed carriage is being developed in Europe, as a ranged unit musketmen are distinctly mediocre in both effect and range.
Pike and Shot, with possible Unique types like Spanish
Tercios, Russian
Streltsy or Swedish
Squadrons, are the 'standard' Melee Unit of the late Renaissance Era. They all have a Ranged Attack also (see the current Persian Immortals unit in Civ VI) with a 1-tile range, and a nominal Anti-Cav Bonus (pikes) - say, about half what a regular PIke unit gets (
@Sostratus can crunch the appropriate numbers better than I - with the 'fire before melee' defense possible, though, a Pike & Shot unit will not be easy to attack successfully)
The Technological Advance to the flintlock musket, or 'firelock' (French
Fusil) and socket bayonet just before the glimmer of the start of the Industrial Era (1700 CE, historically) is HUGE. Range stays the same, but the rate of fire doubles, the density of fire doubles, and the entire unit (bayonet on the end of 5 to 6-foot muskets) now has a Melee Factor.