Light Infantry- The Light Infantry is the best early defensive unit in the game, and is still useful in repelling massed attacks in the late part of the game. However, they are just that: a defensive unit. They are too slow to use in massed attacks, unless the only alternative in the mechanized area is Trikes. A squad (5 units) of Light Infantry can demolish a Trike with ease. So use Light Infantry over Trikes whenever possible. But if you have the option and funds to raise an army of heavier war-machines (i.e. Combat Tanks, Siege Tanks, and/or Missile Tanks) than do so. But always keep several squads of Light Infantry (intermixed with Troopers) around your base at all times. They just might be that one thing between domination or destruction. Light Infantry are trained at and require a Barracks.
Trooper- The Trooper is the anti-vehicle version of the Light Infantry. Whereas the Light Infantry is used against other infantry and lightly-armored vehicles, the Trooper excels in fighting vehicles of all kinds. A squad of Troopers will wipe out a group of Trikes or Quads, and can even take on a Combat Tank or two if they are not run over first. Also, the Trooper is your primary defense against the Atreides Ornithopter Strike. But the Troopers major repellent (besides heavy vehicles, which run them over) is the lowly Light Infantry. The Light Infantry will mow down the Trooper who is used to firing at large, easy-to-hit targets. A small target like infantry poses a problem. So always keep a number of Light Infantry with your Troopers for defense. Troopers are trained at and require an Advanced Barracks.
Engineer- The Engineer is one of those few units that is so powerful, that the game developers purposely make it hard to use. The Engineer works by entering an opponents building, and taking it over. A popular strategy after take-over is to sell the building. Though Engineers fall easily to pretty much any combat unit, they are so potent that you will often find youself diverting your forces from the actual combat units to destroy one lone Engineer. So not only are they good at doing their actual job, but they make great distractions during a huge assault. Though the price is a bit high for an infantry unit, you will soon see that it is quite cheap for the power that it has. Engineers are trained at and require an Advanced Barracks.
Thumper- Not finished. Thumpers are trained at and require an Advanced Barracks. They are allowed only in multiplayer.
Fremen- Though normally an Atreides unit, the Fremen warriors are at best used for mopping up the odd Trike or Quad. Their weapon doesnít seem to have enough power to take on other infantry, but they do a surprising job against vehicles. If you are Atreides and you get them from your Palace, they are cloaked until they attack or get too close to the enemy. But if you find the Infantry Crate (Sardaukar, Fremen (no cloak), Fremen (cloaked), Light Infantry, Saboteur) you only get one cloaked Fremen. The other one is not cloaked, making him pretty much useless. If you can get them, fine. But donít waste money on the Palace just to get Fremen. They just arenít worth it. Fremen are trained at and require an Atreides Palace.
Sardaukar- The only way you can actually use these is by finding the Infantry Crate (see Fremen). Basically, you get all of the pluses of the Light Infantry and Trooper rolled into one, without the obvious disadvantages (they can still get run over though). The Sardaukar is tougher, faster, shoots farther, and has two weapons: a mini-gun for anti-infantry, and a missile launcher for anti-vehicle. The Sardaukar will choose the appropriate weapon when told to fight. But donít waste these guys on just simple raids. You might see two or three of these in your control in any given game (if youíre really lucky!), so donít waste them. Keep them for base defense, to back up your Light Infantry and Troopers. Sardaukar are not allowed normally. They must be found in the Infantry Crate or you must capture an Imperial Palace, at which point they are trained at a Barracks.
Saboteur- These are your suicide units. Given time, the Saboteur will charge up his cloaking shield. Then when you activate it, his cloak will last for an amount of time depending on the number of blocks he has stored (a maximum of five, with about 5 seconds of cloak per block). He can only attack buildings, and only does it once. He walks into the building and blows himself up, taking the building with him. But donít waste Saboteurs on small buildings (Silos, Turrets, Wind Traps, Barracks). Instead, hit the big structures (Refineries, Light/Heavy/High Tech Factories, Palaces, etc.). And if you are lucky enough to get to your enemies Construction Yard, hit the sucker! Finding the Infantry Crate (see Fremen) in the early stages of the game can give you a great advantage over your enemy. Because if you cloak that Saboteur and hit his Construction Yard itís over, and youíve one. However, as with all infantry units, the Saboteur can get run over by heavy vehicles (Combat Tanks, etc.), so avoid them if you can. Saboteurs are trained at and require an Ordos Palace.
Trike/Raider- The Trike is best used for scouting the map. They are a little faster than Quads, but their firepower is limited to infantry and other light vehicles. A group of Trikes is great for quick-defense, because they can intercept the random infantry raids, and are great Engineer/Saboteur killers. But donít buy them for combat. They are too weak. You might as well get a squad of infantry. Basically, once you find your enemy and uncover the main parts of the map, Trikes become obsolete. Unless you find the Cover-Map Crate, in which you need to scout everything out again. The same rules apply to the Raider, which is the Ordos-only variant. It is a little cheaper, a little faster, and a little stronger. But a Combat Tank will still take it down without a problem. Trikes are built at and require an Atreides or Harkonnen Light Factory. Raiders are built at and require an Ordos Light Factory.
Quad- If the Trike is the Light Infantry of vehicles, than the Quad is the Trooper of vehicles. Though it is still in a similar boat as the Trike (light armor, cannot run over infantry) it is much more useful than the Trike, even late in the game. Though it has limited scouting potential, this is not its strong point. Itís strength lies in its efficiency. You get the Combat Tanks weapon on a faster chassis, for about half the price. A couple Quads are great for Harvester hunting. Quads are faster than Harvesters, and they cause a good amount of damage to vehicles. So get three or four Quads and find your enemies Harvesters. Mix these with two or three infantry squads for a small raiding force, or with Trikes for a hit-and-run force. Quads are built at and require an Advanced Light Factory.
Combat Tank- Though the stats for the Combat Tank differs slightly from House to House (Harkonnen Combat Tanks are a little tougher, Ordos Combat Tanks a bit cheaper, etc.), they are all basically the same: a solid can of whoop ass. For a fairly acceptable price you get descent speed, good firepower, strong armor, and infantry-splattering capability all in one vehicle. But never attack with just one. You need at least three to be effective. One or two are sitting ducks for Quads. Mix these with Siege Tanks and/or Missile Tanks for a strong attack force. If youíre Harkonnen, add Devastators to the group. Escorting them with infantry can help, but often times the infantry just get in the way of the Combat Tanks. Combat Tanks are built at and require a Heavy Factory.
Siege Tank- These are good for taking out Turrets in enemy bases before launching your main attack, but not for much else. They have too light of armor and are too slow to be taking on a Combat Tank without protection. Even a Trike or Quad can take a Siege Tank down given time. Usually, just attacking the Gun Turret or Missile Turret with 8-10 Combat Tanks will do the job of the Siege Tank. But if you are against wasting a Combat Tank on a Turret, than you might want a Siege Tank or two. They can run over infantry, but if thatís all you want, get a Combat Tank. On the plus side, a squad of infantry is a good target for a Siege Tank shell. The blast does good damage to infantry. Siege Tanks are built at and require an Advanced Heavy Factory.
Missile Tank- Not finished. Missile Tanks are built at an Atreides or Harkonnen Advanced Heavy Factory. It requires an Ix Research Center. The Ordos cannot build Missile Tanks, but can order them through the Starport.
Deviator- Not finished. Deviators are built at an Ordos Heavy Factory. It requires an Ix Research Center.
Devastator- Pretty much an updated Combat Tank, the Harkonnen Devastator comes with a stronger attack that damages just about everything equally well. It has strong armor, and slowly regenerates damage over time. And if it looks like it is about to die, set it into self-destruct mode. The blast will level buildings and any units in the area. But donít buy a Devastator for that sole purpose. Use it for combat first, than as a bomb. Besides being a bit expensive, the Devastator is slow. Slow as molasses in fact! Even Siege Tanks outrun the Devastator. And the range of the Devastators cannon isnít too great either. About the same as Light Infantry. Yes, they can run over infantry. But they move and turn so slowly that it makes it almost impossible. Support these with Combat Tanks and/or infantry. Devastators are built at a Harkonnen Heavy Factory. It requires an Ix Research Center.
Sonic Tank- The third special vehicle is the Atreides Sonic Tank. It has similar stats to the Siege Tank: slow, weak armor, runs over infantry. However the Sonic Tanks attack is unique. If fires a blast of sonic energy that travels in a straight line for about the distance of the Missile Tank. Anything caught in its path takes damage. Particularly useful against groups of infantry or light vehicles. A row of Silos or a length of Wall is a perfect target for the Sonic Tank. Sonic Tanks are built at an Atreides Heavy Factory. It requires an Ix Research Center.
Harvester- What can I say? Itís not like you would refuse to use them. I recommend having at least three by the mid-game. If you have the resources, get a fourth. This will bring in a steady flow of income, provided you have a Carryall for every Harvester. Also, you will always have at least one Harvester. If it is destroyed, a Carryall will automatically bring in a new one. Harvesters are built at and require a Heavy Factory. You receive one Harvester with each Refinery.
Carryall- The Carryall is the more efficient way of harvesting spice. It circles the working Harvester until the vehicle is full of spice. Than the bird picks it up and brings it back to the Refinery. When the Harvester is empty, the Carryall brings it right back to the spice field again. Once you have one Carryall for every Harvester, block off every entrance to your Refinery with Wall sections. This eliminates the possibility of an Engineer or Saboteur getting their greedy hands on your spice. Carryalls require a High Tech Factory. They fly in from off-screen when completed.
MCV- Short for Mobile Construction Vehicle, the MCV is the most important unit at the beginning of a practice or multiplayer game. By deploying your MCV, you get a Construction Yard which allows you to advance up the tech tree. If you somehow lose this unit before you deploy it, your screwed. Getting an extra MCV is for only one of three reasons: 1) youíre enemy destroyed your first Construction Yard, but luckily you can build MCVís; 2) youíve run out of space on your first rock island, and still have structures to build. So you get an MCV to Ďcolonizeí a neighboring island; 3) you think a base closer to your enemy would allow you to mobilize your army faster. MCVís are built at an Advanced Heavy Factory. It requires a Repair Pad.
Ornithopter Strike- The Atreides have the best air-strike option in the game. It takes about the same amount of time to complete as the Harkonnen Death Hand Missile, but it attacks the target area three times! And the area affected by the bombs is very big! Great for wiping out an incoming enemy army, even better if used to level your enemies base as a prelude to an attack. Target building clusters, like your enemies Wind Trap or Silo grids. Hitting Factories, Refineries, or other advanced buildings is even better. The attack will not destroy most buildings, but it will cause substantial damage that will open up an avenue of attack. Ornithopter Strikes require an Atreides Advanced High Tech Factory. When completed, you choose the target for the strike. The Ornithopters fly in from off-screen and attack the target area.
Death Hand Missile- The Harkonnen Death Hand Missile is the toughest weapon to use right. But when one is wielded by able hands, it becomes a very fearful weapon. Though it takes longer to attack than the Ornithopter Strike, the Death Hand Missile causes so much damage it makes it well worth the wait. The area affected is rather small, about a 3x3 area of concrete slabs. But anything in that area is bound to die. Even larger structures like Refineries and Construction Yards fall to the Death Hand Missile. I recommend spending the cash to get a Harkonnen Palace for just this weapon. Death Hand Missiles are built at and require a Harkonnen Palace.