Basics
Positioning
Unit positioning, alongside unit composition and use of upgrades and powers, make up the majority of what decides the outcome of a match.
Aggro/Targeting
Units will always target the unit they can reach in the shortest amount of time. This is typically the closest unit, but not always - units with slow turning speeds may attack a more distant target instead of a closer target that would require that unit to rotate towards it. For example, if a unit would take 3 seconds to get in range of a tower but 3.5 seconds to turn around and attack a unit, the tower will be targeted. (There might be more factors that affect what a unit targets, such as whether or not the unit is being shot at by a possible target) But as soon as unit attacks a target, it will continue to attack that target as long as it is alive and in range.
There is one exception to the above target system is the Steel Ball upgrade Heavy Target, which allows them to prioritize attacking the unit with most HP in range. The Aerial Specialization tech also can effect targeting, because the extra range against air units may affect a unit's target priority.
Unit Speed
Keep in mind that units move at different speeds and will therefore enter attack range at different times. For example, in order for a Marksman (slow) and a unit of Crawlers (fast) to enter attack range at the same time, you will need to put the Crawlers at least 5 or 6 tiles behind the Marksman in order for the Crawlers to be slightly ahead of the Marksman when they reach combat. Ideally, you want your entire army to enter combat at roughly the same time - a unit that sprints ahead of the rest of your army and charges into every ranged unit your opponent has is a waste of resources.
Frontline
Units in the front take all the damage therefor tanks and spam should be in the frontline. These units are typically all that stands between your units and your opponent's backline units.
Backline
Units in the backline are usually protected from damage when placed behind frontline units. DPS units and snipers will typically be deployed here.
Range
Range is an important stat. The unit with the lager range usually gets the first shot, which is particularly important for powerful but fragile units like the Marksman. Units with short range can also affect the battlefield. Melee units will always charge the enemy frontline (the closest enemy) and become the target for the enemy's ranged units. Steel Balls also have a short range and will frequently end up in the frontline.
Unit Types
Spam/Chaff (Infantry and Light Tanks)
Cheap units with high unit sizes fall under this category. While they can inflict significant damage, the main benefit of chaff units is to draw fire away from your larger or more valuable units.
Crowd Control/AoE
Units able to destroy multiple low-HP units simultaneously fall under this category. These units allow your single-target damage dealers to freely target larger units instead of chaff units. Crowd control units usually trade lower damage per shot for an area of effect attack able to hit multiple targets.
Arclight, Stormcaller, Vulcan, Mustang, Sledgehammer
Damage Dealer
Sniper
Snipers deal a high amount of damage to a single target and may take them out with one shot. These units typically have a low fire rate, making them weak against spam.
DPS
DPS deal a lot of damage over time at the cost of low initial damage. These units can potentially damage large units more efficiently than snipers but are still ineffective against chaff. The Melting Point is a quintessential example of a DPS unit - devastating against single targets, poor against large groups unless upgraded.
Steel Ball, Melting Point, Crawler
Tank
Units that can survive a lot of damage fall under this category. Tanks are vulnerable to DPS and Sniper units due to their high damage output, but can effectively draw fire from AoE attacks.
Giants, Rhino, Steel Ball, Sledgehammer
Air-Units/Flyers
Air units are unique in that they are immune to ground effects (e.g. acid/fire trails) and cannot be attacked by most ground units. These units are typically more fragile than their grounded counterparts (e.g. Overlords have less HP than the other 3 giants).
Anti Air
While there are only a limited amount of units who can attack air units, all of these units present a credible threat to flyers in addition to being competent ground units as well. All air units have the ability to attack ground and air units. The importance of having anti-air units cannot be overstated - without them, a single air unit can do a lot of damage uncontested and even singlehandedly win the round.
Marksman, Mustang, Fang, Melting Point, also with Tech Arclight and Fortress
Special
- The Hacker is a special unit who can overtake enemy units and make them change side. Highly effective against when your enemy fields large numbers of giants or single units like Rhinos.
- Some units can spawn more units.
- Electromagnetic Shot disables tech of the target. Disabling the upgrades of enemy units is always useful, but this upgrade is mandatory against certain tech upgrades (e.g. Rhinos with Self-Destruct, any unit with Armor Enhancement)
- Jump Drive is a tech for all air units that let them change position during setup phase. Useful for making surprise attacks on enemy flanks and then moving them once your opponent deploys units on the flanks to stop your attack.
- Acidic Explosion, Incendiary Bomb, Sticky Oil Bomb will create a hazardous effect on the ground and effect all units standing on it. These bombs are also one of the few ways to deal AoE damage to units protected by a bubble shield - if the bombs explode in front of a shielded unit, the unit will still be damaged when they walk over the hazardous terrain.
