Thank you all for the great comments!
Here's an image portraying Romans versus the phalanx:
I'm not exactly sure how the Romans were able to defeat the phalanx (I'm not an expert in this part of antiquity), but if I recall correctly there are reports of Romans retreating to the high ground during battle which was a huge disadvantage for the phalanx. (If the hill is steep, the sarissas have to be held more vertically. This way, a quick counterattack would mean that the sarissas couldn't be lowered on time or lowered enough to be effective in battle.)
Most Roman troops carried the heavy scutum (more rounded than the later rectangular version) which meant that the sarissas wouldn't be able to penetrate the shield. I suppose the scutum could be used to form a slope, so that the spearheads would go upwards, forcing the phalangites to go in close quarter combat. (And Romans were experts at this.)
The phalangites' weaponry consisted of the sarissa and a short sword, while most Roman troops used several projectile weapons. (The first line of the army, the velites, were designed to throw several (up to eight!) javelins and then retreat. The hastati and triarii both carried two pila.) A rain of projectiles would certainly be able to break the phalanx up enough to force them into close quarter battle.
A last point that would give the Romans an edge is the fact that a Macedonian line would be made up of several blocks (the phalanxes) with space in between. The phalanx is basically a big block of men and would be difficult to manoeuvre. The Romans also had a large amount of troops, but they would have been divided into a lot of smaller units. (I'd say the centuria but I'm not sure if this term was used before Marius' reforms.) This way, the Romans might have simply outmanoeuvred the phalanx. (The phalanx got its power at the front, where all the weapons were pointing the same way. The sides and back were unprotected and it was very difficult to change the direction of the sarissas quickly. (Whereas the Romans would only be carrying their gladii (short swords) by then.)
In the end, the phalangite was a feared soldier when in formation but once the formation broke, the infamous sarissa would become a clumsy burden. (I can imagine that the middle and last rows wouldn't even have had the space to drop the sarissa, so that every row had to fight on its own.) Once in close quarter combat, the Roman soldier would have the upperhand. In the end, the Roman army proved superior, both in tactics, organisation, equipment and training.
WarriorOfToys: I'm also planning on using several helmets, I was thinking about using the 'Egyptian/Mongolian' helmet, either by itself or on a different helmet. The Macedonians do seem to be a lot more uniform than the Greek hoplites were.
Cheers,
Gaetano
