In MGM and XGM I have represented hypaspists as athletic hoplites who have been re-equipped to perform various functions in support of the phalanx. In real life matters were a little more complicated. So what were hypaspists, and how were they equipped? Poliorcetes kindly provided the following answer on the totalwar.com forums:

This is a complicated question because there isn't much good evidence either way, and because it all depends what you mean... when everyone talks about Hypaspists they usually mean the Hypaspists under Alexander (the Great). Bear in mind that RTW starts 50 years after Alexander died, and the Macedonian army (and all the armies derived from the Macedonian eg Seleucid and Ptolemaic) certainly changed in this period, so that saying what the Hypaspists were like under Alexander (even if we could) doesn't necessarily tell us much about what the equivalent unit was like in the 3rd and 2nd C BC.

That said, here's a summary of what is known about Hypaspists, 'Royal Pikemen' or whatever, in case it is of interest (it interests me at any rate...)

Hypaspist means 'Shield Bearer', and seems originally to have referred to a small group of bodyguards. The name was then extended to the Hypaspists as we know them under Alexander (just as the name Companions was applied to the whole of the cavalry, and Foot Companions to the whole of the infantry - so this is an honorific title that doesn't tell us anything about how they were equipped). They were 3000 strong under Alexander, and as plenty of people have said, they fought on the right flank of the main phalanx (Foot Companions) in battle, and were also used for all sorts of special missions, forced marches, assaults etc, anything where the best troops were needed.

Nothing can be said with certainty about their equipment - in battle, no distinction is made between their role and that of the Foot Companions, which suggests they might have been armed similarly, yet their use in assaults and forced marches might suggest some lighter equipment. It always used to be said that Hypaspists were armed more like classical hoplites (ie big shield, shortish spear), but there is no evidence for this and it makes no sense to me given that they were used for 'light infantry' duties and hoplite equipment is by definition heavy. Macedonian infantry depicted on the Alexander Sarcophagus carry big hoplite shields, but there is no reason to suppose these are Hypaspists rather than Foot Companions. As DimeBagHo said above: "I can only guess that they carried different equipment depending on what they were expected to do." That is my guess too.

In the course of Alexander's campaigns the Hypaspists started to be called the Silver Shields (Argyaspids), and it is under this name that they are known in the wars of Alexander's Successors. Here they were an elite unit that again seems to have fought as part of the phalanx, on the right wing.

There then follows 80 years of silence in which precious little is known of the Hypaspists or Argyraspids, until the histories of Polybius pick up again around the 220s BC. Now a unit called the Argyraspids appears as the elite infantry of the Seleucid army - although again nothing can be said with certainty about their equipment. They were 10,000 strong and fought as the right flank of the phalanx for example at Raphia under Antiochus III. This is the unit that was re-equipped as Roman legionaries under Antiochus IV (as represented in RTW - good research, CA).

In Macedon itself the picture is a bit more confused. In the Antigonid army (the Antigonids being the dynasty that ruled Macedon, descended from Antigonus One-eyed) there is inscriptional evidence of hypaspists acting as a sort of military police, but this tells us little. In Polybius, the elite unit of the Antigonid army is called the Peltasts - which might seem rather surprising - and is still 3000 strong. They are described as acting much like Alexander's Hypaspists, used for all sorts of special duties, but they also fought as part of the phalanx and no distinction is made between their role in battle and that of the rest of the phalanx (now apparently called Chalkaspids - Bronze Shields). The best evidence for them comes from the battle of Pydna, where they were the first unit to engage the Romans and where they definitely carried the sarissa (pike), and seem also to have carried smaller than usual shields (which is probably why they are called Peltasts, a pelte being a light shield).

To summarise all this in RTW terms - nobody knows how these units were equipped and your guess is as good as anyone else's :) . More helpfully, first of all it's probably best not to call them Hypaspists - in the Antigonid (Macedonian) army Peltasts is more accurate, and Royal Pikemen is a fair description if not really historically accurate. In the Seleucid army they are Silver Shields. As to equipment - I think CA made a reasonable compromise with their Royal Pikemen given what little is known for sure. But they definitely should carry the pike in battle and fight in phalanx. However, to represent their use as assault troops etc they could perhaps be given a high secondary weapon ability. Their shields should be smaller than those of the main phalanx, though unfortunately RTW seems to equip Macedonians with dinner plates in place of shields - this is wrong. They should also be faster and more manoeuvrable than the main phalanx, but I don't think there is any easy way to represent this in RTW.

I can provide references for all this if anyone is interested, and wants proof I'm not talking entirely out of my bottom.

Here endeth the lesson...

...almost. Here are the references:

@DimeBagHo - here's some material for you about Macedonian peltasts. I have a lot more of this, and a lot of the evidence for shields etc is pictorial, so if you'd like to discuss further feel free to pm me.

Pol iv.64 (Philip V v. Aitolians, 219 BC)
The Aitolian horse rallied and ventured to meet him at the ford of Achelous, believing that they would either stop his advance altogether or inflict much damage on the Macedonians while crossing the river. The king [Philip], fully understanding their tactics, ordered his peltasts to enter the river first and to cross it in close order, keeping in their companies (speirai) and with locked shields. His orders were obeyed: and as soon as the first company had made the crossing, the Aitolian cavalry attacked it. But they could make no impression on it, standing as it did in close order, and being joined in similar close order, shield to shield, by a second and third company as they crossed. Therefore they wheeled off and retreated to the city.

Pol v.25 (Philip V, 218 BC)
Leontius, Megaleas and Ptolemy, being still persuaded that they could frighten Philip... took this opportunity of corrupting the peltasts and what the Macedonians call the agema, by suggesting to them... that they were not receiving their fair share of the plunder.

Pol v.28 (Philip V campaigns against Sparta, 218 BC)
When he had got within distance of Lycurgus [the Spartan king], Philip at first ordered the mercenaries to charge alone: and accordingly their superiority in arms and position gave the Spartans the upper hand at the start of the battle. But when Philip supported his men by sending his reserve of peltasts onto the field, and ordered the Illyrians to charge the enemy on the flanks, his mercenaries were encouraged by the appearance of these reserves to renew the battle with more vigour, while Lycurgus's men, terrified at the approach of the heavy armed soldiers, gave way and fled, leaving a hundred killed and rather more prisoners.

Pol xviii.24 (Battle of Cynoscephalai, 197 BC)
Philip himself advanced with his peltasts and the right wing of his phalanx, beginning the ascent of the hills with great rapidity... a soon as his first files reached the summit, he deployed his men into line by the left, and occupied the high ground... Taking the skirmishers, infantry and cavalry, he massed them all on his right wing, while he ordered the peltasts and heavy armed to double their depth and close up to the right. By the time this was done the enemy were close at hand, so the order was given to the phalanx to lower spears and charge, and to the light infantry to cover their flank

Livy xxxi.26 (Philip V v Romans 200 BC)
After a day's interval, the king [Philip] was ready to join battle with all his forces of cavalry and light infantry, and at the same time he had concealed his caetrati (they call them 'peltasts') in ambush in a convenient spot between the two camps.

Livy xlii.51 (Persues parades his army at Citium, 168 BC)
He pitched camp before the city and drew up all the soldiers on the plain. The total of all was 43,000; about half of these were phalangites.... Then there were 2000 chosen from all the caetrati for their strength and the vigour of their youth; this unit they called the agema... The leader of the other caetrati, about 3000 men, was Antiphilus of Edessa.

Livy xliv.41 (Battle of Pydna, 168 BC)
If they had attacked frontally in solid line against an orderly phalanx, as happened to the Paelignians who at the beginning of the battle recklessly met the caetrati, the Romans would have spitted themselves on the spears and would not have withstood the solid line.

Plutarch, Aemelius 18-21 (Battle of Pydna)
Next to the Thracians the mercenaries advanced to the attack, with equipment of every type... Next to these thirdly was the agema, picked men, the flower of the Macedonians for youthful strength and vigour, gleaming with gilded arms and fresh scarlet tunics...As the attack began Aemilius came up and found that those in the Macedonian agema had already planted the points of their sarissas in the shields of the Romans, who were thus prevented from reaching them with their swords... And when he saw the other Macedonians drawing round their peltai from their shoulders and with sarissas levelled holding off his shieldmen (thureophoroi)... amazement and fear took possession of him.... Salvius, the commander of the Paelignians, snatched their standard and hurled it in amongst the enemy. Then the Paelignians... rushed after it and dreadful losses were inflicted and suffered on both sides. For the Romans tried to thrust aside the sarissas with their swords, or to crowd them back with their shields, or to push them aside with their hands, while the Macedonians, holding them firmly advanced with both hands, and piercing those who fell on them arms and all, since neither shield nor breatplate could withstand the force of the sarissa, hurled back the Paelignians and Marrucinians... [however, the Macedonian line eventually gives way]... Finally the 3000 picked men, who remained in order and kept on fighting, were all cut to pieces.