An engineer is a unit that has an engineering suite. An engineer can build, repair, reclaim, capture, and assist. Although it is unarmed, it can attempt to reclaim enemy units, which gradually decreases the unit's health. All engineers are amphibious, allowing them to cross water.
There are three tech levels of engineers. Tech 1 engineers can build tech 1 structures. Tech 2 engineers can build tech 2 structures, as well as tech 1 structures. Tech 3 engineers can build all structures, as well as experimental units.
Higher tech level engineers have higher build rate than lower ones, expending resources at a correspondingly greater rate. A Tech 2 engineer builds twice as fast as a Tech 1 engineer, and a Tech 3 engineer three times as fast as a Tech 1, or 1.5 times as fast as a T2.
Tech 1 Engineers only build half as fast an ACU. However, an ACU with a Tech 2 upgrade builds 3 times as fast as a Tech 2 engineer, and a Tech 3 upgraded ACU, 6 times as fast as a Tech 3 engineer (or 18 times faster than a Tech 1 Engineer!)
Engineers of any Tech build exactly 1/4 the speed of a factory of the same level. This means that it takes no more than 4 engineers to double a factory's build speed, and annul the need for a new one.
HP* = Calculated as an average value of all 4 factions
Production speed* = Multiple values indicate upgradeable units
In sheer construction time per resources spent, the Tech 1 engineer is best, followed by Tech 2, Tech 3 and finally, SCU. However, Tech 1 requires more micro managing, and die much easier. SCUs are extremely expensive, but have really good build speed and they shine on the battlefield: They are the only engineering units that can build things while taking a beating, making them the perfect combat engineer. They excel at creating point defense creep.
Engineers of all 4 factions cost the same, build at the same speed, move at the same speed, build at the same range, and are overall equal. Only their Hp differ slightly, the Aeon's being the weakest, and the UEF's the strongest. Also Both Aeon and Seraphim Engineers hover, making them immune to torpedo type weaponry.
Aeon engineers, as well as their SCUs also have the ability to sacrifice themselves—the engineer is destroyed but it instantaneously gives its own mass and power cost to the object being built. This is not only useful to speed up the building process of a must-finish object, but it is a easy way to recycle near death engineers, or to get rid of excess T1 engineers late game, without wasting mass.
There are other units with engineering suite, especially in the UEF faction, and a few in Cybran. There are the fixed helper-type building engineers, which automatically repair, build, assist or reclaim any units in their range, UEF T2 Engineering Station: The Kennel and the Cybran T2 Engineering Station: The Hive, and their respective upgrades. The UEF also has some unique flying Engineer drones, the C-D1 "Rover", C-D2 "Rover" and the C-D2 "Rover-2". These are built in limited numbers by the ACU and the Kennel.
For details about a specific engineer, click the corresponding icon in the Unit Navigational Box, at the top of the page.
For a list of all engineers, see the engineers category.