Infantry (Artridies and Ordos)
Cheap but weak unit. Only useful in the first levels, and must always be used in great numbers. You will be able to build squads if infantry which will increse firepower and makes your units easyer to move.
Troopers is the Harkonan infantry. Armed whit basookas they have far more firepower then the standard infantry used by the artridies and the ordos. Can also be used in squads.
Trike (Artridies and Ordos)
The light trike is the fastest ground unit in the game, but it has no armour. Best used against rocketlaunchers whitout cover ( rocketlaunchers can't hit at point blank range). Needs a 2 to 1 superiority against Harkonan quads and can only function as a diversion agains tanks.
The Ordos trike is called raider trike and is faster (and more expensive) then the standard trike.
Light armoured vehicle. have better firepower and armour protection then trikes, is used in the same way, but in group they can take on single combat tanks.
To quote the harkonan mentat: 'The combat tank have adequat armour and firepower.' It is a cheap and fast tank, best used as cover for rocketlaunchers.
Heavy siege tank (Harkonan and Ordos)
The most commonly used tank in the later levels. Whit heavy armour and a BIG gun, used to spearhead an attack it has a devistating effekt.
Rocket launcher (Harkonan and Artridies)
Having an enourmus effekt agains both units and structures it should be used as support fire, send your tanks in as spearheads and let the rocket launchers shoot over them. As the unit have weak armour, sending them alone against anything but other rocket launchers without cover or harvesters far from the base is suicide.
This unit rounds up spice and takes it back to the refinery. Although heavely armoured it has no wepons and can't defend itself (as all tracked vehicles is can crush infantry), so if it's not operating close to your base you should consider having a small force in it's operating area to protect it from enemy attacks, and kill or discurage sandworms (if you start losing your harvesters the battle will be lost as well).