The Unique Power of the ACU
Supreme Commander is full of heavy hitting battle mechs and experimental ultimate units that can crush armies beneath them (literally!) but no unit is quite like the ACU. Its there at every game start, the plans to lay the groundwork for an entire military loaded into its database. It is equipped with sufficient metal and energy stores to get that force off the ground in a sustainable manner. And when battle comes it can smash inbound attacks and defend its nascent base.
Of course the ACU isn't without its downsides. It can't fly without assistance and worst of all, if it takes too much damage it explodes in a cloud of nuclear fire, taking nearby units and structures along with it. In Supreme Commander, ACU death also generally means that the game is lost – whether instantly in the case of campaign or sudden death multiplayer missions or later as the lack of the ACU's unique supportive features are felt across the entire in-game economy.
Due to this critical weakness many players, once the basic framework of a base has been constructed, send their ACU behind a mountain or under a safe patch of water and leave it hidden for much of the game. This can be effective, but is in truth a waste of the ACU's power. Utilizing the ACU's incredible strengths while balancing out its weak points can be the key to victory – and some skilled players even successfully make the ACU the core of their army.
ACU Upgrades: Make the ACU a Nexus
The upgrade pathways available to all ACUs in SupCom are similar although each faction's fully upgraded ACU will exhibit key differences that may inform a player's choice of upgrade path. In general, the armored command unit is upgraded to be the heart of a base or the heart of an army. Fully upgraded units intended for offensive operations can sport an energy shield, upgraded weaponry including fast firing cannons or lethal tactical missiles, and even a teleportation device. Defensive minded players can alternatively upgrade the ACU to be able to build any tier structure and even experimental units. Coupled with this building ability can be increases in native resource production and build rates. The defensive ACU can be one of the top resource generation structures and a glorified tier 3 engineering unit to boot.
It takes a significant injection of resources and time to upgrade an ACU, but most experienced players will effect begin upgrading their command unit as soon as their economy can handle the strain and they judge there will be a few spare minutes to expend in the upgrade. When ACUs are upgrading they're immobilized and fairly conspicuous, so poor timing can lead to a quick end to a game of Supreme Commander, ACU death being delivered by a quick strike launched by a capable opponent. For this reason upgrades should be done in a protected area and not too close to the front line of battle. Strategic bombers and nuclear missiles can do a great deal of damage to an ACU in mid-upgrade.
Using the ACU Offensively
Offensives led by the ACU can be extremely risky but equally rewarding. A fully upgraded combat ACU is a frightening sight to behold – with energy shields and top line weapons even experimental units can have trouble with a fully upgraded armored command unit.
Specific employment of an ACU in an offensive role will depend largely on the faction. Aeon commanders can be spotted in the thick of fighting – once upgraded with an energy shield and fast firing laser few units can face an Aeon ACU head on. Especially when backed up by tier 3 assault mechs, air defenses, and some additional shielding from mobile units the Aeon command unit can act almost like an experimental unit, though it should generally still not be employed in full on frontal assaults.
UEF commanders tend to use their ACU as a glorified artillery piece. Tactical missiles can do extreme damage to a structure or group of units at long range. An energy shield can give the ACU sufficient survivability to escape to friendly lines in an emergency, but otherwise the ACU can sit at the back end of a line of friendly units and pound away at defenses with tac missiles much like a cruiser. Combine a UEF ACU with the mobile factory ultimate weapon and you have a highly mobile, extremely defensible firebase.
Cybran ACU employment in an offensive role is yet again different in Supreme Commander. ACU death is a particularly dangerous problem for Cybran commanders because their ACU is designed to be used as a fast and hard striking guerilla unit. It can be upgraded with a stealth field generator that allows it to remain invisible to all but omni sensors. Its arm can accept a sweeping microwave laser identical to that used in the Monkeylord ultimate unit. These combined upgrades mean that the Cybran ACU can actually sneak inside of an opposing base or attack group, decloak, and annihilate everything near to it before an opponent can respond. This incredible power is offset somewhat by the lack of a shield – a Cybran ACU has to be carefully employed to prevent destruction in guerilla ops.
Defending Against ACU Assassination
There is a strong incentive for players to kill an opponent's ACU in Supreme Commander. ACU death can be effected by any number of platforms fairly quickly – experimentals can smash an ACU in seconds, nuclear missiles can turn one into an inferno, and a mass of mid-level tanks backed up by artillery can beat one to death. Probably the most feared ACU-killer is the strategic bomber. When sent after a commander detected by recon units in decent numbers – 5 or 6 usually, and preceded by tier 3 fighters to draw fire – the strategic bomber strike can immolate an ACU in seconds.
But just tucking the ACU away to keep it safe is a waste of resources. Even if the ACU isn't sent on the offensive enacting defensive upgrades to make it a super-engineer are absolutely key. The command unit can be set to build any other unit and can do so as effectively as a mass of tier three engineering units. Setting the command unit to build experimentals with the support of some other engineers can provide late game domination to any player with the economy to support the resource output necessary.
One final possibility to consider: equip the ACU with a teleportation device and the economy to power the thing. The ACU can then be sent to draw an opponent's attention all across the map: a player who likes to play assassin can be lured into sending units all over the place, dispersing forces, while the target ACU just teleports away whenever danger approaches.
One way or another, the armored command unit should not be put on a shelf and admired. Used properly it can make all the difference in a close match.