Repair guns are critically important tools, as they are the only weapons capable of healing vehicles, buildings, and infantry. They can also disarm all types of C4 and beacons, making their deployment vital once a beacon has been dropped. They are so important, that if nobody on a team is willing to use them, that team will lose the game very quickly. This article teaches you how to use them.
 Repair Gun Types
There are two kinds of repair guns. Engineers carry the weak repair gun and Hotwires/Technicians are issued a stronger, longer-ranged version. Both of these versions differ from the repair guns found in the single player mode though, which have an alternate fire mode that causes damage. However, this is not the only difference; the basic engineer and advanced engineers's equipment loadouts are somewhat different.
Engineers (both GDI and Nod) carry repair guns as standard issue. This (along with their Remote C4) makes them useful on the battlefield. The fact that engineers are free and readily available at any time makes them useful as support units when rushing with tanks/APC's, or defending the base against an enemy rush or bombardment. However, the repair gun of basic engineers is noticeably slower at repairing than a Hotwire/Technician's Advanced Repair Gun, and has slightly less range.
Hotwires and Technicians have the high power repair gun, but cost 350 credits and require a functional Barracks or Hand of Nod. They also have an additional 100 units of Health, an extra Timed C4, and six Proximity C4 (though they start with only five; subsequent refills will net you the full six). Their repair gun does it's work far faster than the basic engineer's, to the point where it can become a critical issue in certain situations, such as a mass bombardment hitting a building, or a beacon that has counted most of it's timer down. They are also better at supporting your team's tanks in the field, however you should look at the situation before going out onto the field as a Hotwire/Technician, as you are a prime target for the enemy and vulnerable to sniper fire, which will result in your 350 credits down the drain; it's not a lot, but it can add up.
The items available to these units are as follows (with non bolded text being available to regular engineers, and bolded text being available only to Hotwires/Technicians);
- Repair Gun or Advanced Repair Gun
- Remote C4 x2
- Timed C4 x1 or x2
- Proximity C4 x6
- Automatic Pistol
- 100 Health and 100 Armour, or 200 Health and 100 Armour.
For how to use the Proximity C4, look at Laying Proximity C4 and Advanced Mining. For how to use the Pistol, look at the Pistol guide. For strategies to use with the Timed C4, look at the Structural Demolition Guide.
Hotwires and Technicians have a fairly low price, given their extreme usefulness. If you want to defense your base, support a vehicle, disarm a beacon, or destroy an enemy building single-handedly with your C4 loadout, Hotwires and Technicians are the best choice. However, offensive use of Advanced Engineers requires some thought, as the 350 credit expenditure can add up, and your advanced repairing may well be needed elsewhere on the map. For field deployment to support tanks, the use of regular engineers is recommended unless there is a low risk of snipers.
 Repair targets
Repair guns can repair damaged buildings, vehicles, and infantry. They cannot be used to repair yourself, or a destroyed building. Also, it causes damage to beacons and C4 in the form of "Disarming" them, but it is not possible to disarm your own team's C4 or beacons unless the Frendly Fire option is enabled. Be warned that the repair gun does not differentiate between friend and foe - shoot an enemy with your repair gun and it will heal them. Sometimes, griefers will do this to enemies in order to stymie the efforts of your team - report them to a moderator if one is available, as this kind of behaviour is not tolerated by anyone with at least half a braincell to their name, and will result in the banning of the offender. (Beacon rushers can use that to their advantage by standing in between a disarming Engineer/Hotwire/Technician and the beacon they are defending. some servers allow this, so chech the rules regulary)
The enemy can damage your buildings in a whole host of ways, but you can counteract this by using the repair gun to fix the damage to the building. You can repair a building directly in one of two ways - by simply shooting the building with your repair gun, or going inside and finding the Master Control Terminal - this is the focal point of any building and takes double damage from everything. Fortunatley, this applies for repair guns too, allowing you to repair the building at twice the rate. However, you should give some thought to the allocation of manpower to repair a building, dependant on the situation. Too many people, and you lose the advantage on the field - too few and you risk losing the building. To see the state of your (and your enemy's) buildings at any time, press and hold K, and look at the damage meters on the sides of the screen. You can also signal your teammates using the radio warnings "Building needs repair!" (Ctrl+1), and "Defend the Base!" (Ctrl+Alt+6). (You can specifically signal the refinery or power plant with Ctrl+Alt+9 and Ctrl+Alt+0 respectively, but any other building will have to be referred to as either "that structure" (Ctrl+Alt+8), or type the name out.)
- If a building is damaged, but the attack on it has subsided and there are no other outstanding situations to deal with, then you can make do with a single non-advanced engineer.
- If a building is heavily damaged (as in yellow health or below), and there are no other outstanding situations to deal with, then you may want more than one, as an attack could occur at any time, causing further harm to your building.
- If a building is under active bombardment from tanks or artillery/MRLS, you will want either a single advanced or two regular engineers to maintain the building's condition. Note that they will need to stay at the building throughout the bombardment, so you will need others to destroy the attacking vehicle.
- If the situation is any worse, such as red damage, massive bombardment or the likes, two or more advanced engineers are recommended. Losing any building is a severe impairment to your team.
In addition to watching the building's health directly, you have to watch out for certain other hazards. In paticular, C4 on the Master Control Terminal can quickly cut down a building's health to nothing - infact, a single Hotwire/Technician's loadout of two Timed C4 and two Remote C4 is enough to destroy a building in one go. If you see charges on the Master Control Terminal, you MUST disarm them at once, in the order of Timed, then Remote, then Proximity (though you will rarely see enemy Prox C4 placed on your MCT). The damage done by Timed C4 is roughly 40% of the building's health, meaning you only need three charges to completely destroy it. Fortunatley, C4 tends to disarm very quickly once targeted. You will, however, need to keep your distance in order to avoid being possibly blown up by the C4. Also, you will need to watch out for the enemy who planted it in the first place - they will not want you disarming it and will very likely attack you, and it is extremely hard to disarm C4 and dodge attacks at the same time, given C4's miniscule size. So bring some support with you, if you can.
Beacons are quite similar to timed C4, only their placement barely matters at all due to the immense damage they deal; one beacon will take out a building almost without fail. Having said this, the placer will usually place it somewhere that is awkward to get to quickly, along with a piece of Timed C4 nearby to discourage you from disarming it. On flying maps, roofs should be checked out first - follow the beeps to find the beacon. However, a smart beacon planter will hide nearby and attempt to kill anyone disarming the beacon, making it very difficult to do so for the same reason as C4. So again, it is recommended you bring support - but bear in mind the beaconer will likely aim for you no matter who shows up, as you are the biggest threat to his beacon succeeding.
As a bonus for keeping your team out of trouble, repairs will give you points and credits. However, they are somewhat less than you would get for damaging the building, but a little sacrifice such as that is worth it to prevent losing the battle altogether. Either way, they can rack up quite quickly, giving you access to things to buy once your duties at the building are finished; perhaps you could treat your teammates to a few free tanks to regain the advantage. Disarming C4 gives very little points or cash, but disarming beacons gives a large sum of both.
Vehicles are in good shape when first purchased, but can quickly accumulate damage, as they are prime targets on the battlefield. Thusly, they will need support, or they will be destroyed and the credits sunk into them will be wasted; that's where you come in. Vehicles can be repaired just like anything else, irrespective of who they belong to (if anyone at all). However, unlike with buildings, it is unlikely you can out-repair a sustained bombardment on the vehicle - it is down to the driver to get out of harm's way and signal that he needs repairs (Alt+1). Repairing vehicles that defend your base is a lot easier than repairing vehicles on the field, as you are generally not as susceptible to sniper or assault fire when using cover properly. You can even repair your own vehicle by jumping out and hitting it with your repair gun - be aware though that positioning matters a great deal when doing this, especially if you are GDI, as vehicles can quite easily be stolen, giving the enemy a very large advantage.
 Repairing your own Vehicle
When you repair your vehicle, you have to get out, leaving it open to be taken by anyone unless you had someone else in the vehicle with you. Also, unlike the vehicle you are not made of metal, making you much easier to kill, especially with a headshot. Be aware that if a sniper sees you, he will probably make a priority target of you, in order to allow your vehicle to be stolen by his teammates (or possibly himself if he's close enough). With this in mind, you should position yourself accordingly, using the vehicle itself as cover. However, don't think only about snipers - you must watch out for people approaching on foot to take your vehicle, so make sure you have as good a view of your surroundings as possible.
GDI have an additional disadvantage in this case due to Nod's Stealth Black Hand - the ultimate vehicle thief. Under no circumstance should GDI personnel get out of their vehicle to repair it without being sufficiently covered and protected by either teammates, or the base defenses. If you see a GDI teammate in the field doing this, tell them to get in the vehicle (Radio command Ctrl+2) as they are creating a liability to your team. Nod does not have this factor to worry about, but they should still be careful - having their own stealth tanks turned against them leads to embarrasing situations.
If you are in the field and see your teammate get sniped or killed while repairing their vehicle and there is no-one around to take command of it for them, destroy it! They may whine or get angry at you for doing so, but allowing it to fall into enemy hands is far worse than having to buy a new one. Infact, stolen tanks actually count towards YOUR team's vehicle limit, giving you the double disadvantage of having less vehicles to field, and Nod having a weapon they cannot normally access. If one of your team's tanks is taken over, destroy it at all costs. A smart enemy will likely take any measures it can to prevent it's destruction, but your team is at a major disadvantage until it's gone.
Be aware that though your vehicle can be hit with C4, getting out to repair it is largely a bad move. Light vehicles can often be destroyed outright with a single bomb, but heavier vehicles take several. Sometimes, when C4 is stuck to a vehicle, it can land in a place that makes it hard to hit, or sometimes just visually disappears outright. Therefore, getting out of your vehicle to fix C4 is pretty much a vain effort, and you might as well just take the punch or account for it as well as you can. If you get hit by a beacon, give yourself a firm kick in the head. =)
 Repairing a teammate's Vehicle
This is where vehicle reparation really shines. In a prolonged siege or tank battle, there's nothing worse than having to pull back every so often to fix your tank, creating a gap in your front lines and risking vehicle theft on maps with no base defences. However, if you have support engineers repairing you as soon as you pull back (or sometimes just repairing you continuously the whole time), it makes the whole process faster and much more efficient, allowing for a much more solid presence on the front lines. Having multiple engineers can render tanks practically invincible (Mammoth Tanks are a good tank to do this with). However, they will still need to watch out for snipers, and the driver shouldn't become TOO reliant on the engineers, and should still take care to know when enough is enough, and fall back when risks on the front lines become too great.
Repairing infantry is pretty much a redundant move, as more often than not, a damaged infantryman will also be fairly low on ammo, which can only be fixed by a refill at the base - putting them back at full health, armour and ammunition straight away. There are exceptions, of course (such as engineers repairing each other to cross tiberium on foot), but they are few. Use your own judgement whether it's worth repairing infantry or not. If you come upon enemy infantry, just use your pistol. Hitting them with the repair gun will heal them, and give you minus points.
Proximity C4 is like any other C4 in that it can be disarmed, though its purpose is defensive rather than offensive. Getting into the base is one thing usually, but disarming the mines can be very tricky. Often, there will be many mines clustered in one place. The key factor here is time - if there are many distractions going on, your chance of successfully disarming all mines and infiltrating a structure are much better. Even so, be aware that respawns and passers-by can easily catch you out, due to the noise that the repair gun generates. Multiple engineers are recommended for de-mining areas, as many hands make light work. You could also defuse some of the mines and then jump on the rest, sacrificing your health for speed. Be aware that nearby troops may come to investigate the explosion, though. Also, make sure you have disarmed enough mines to do this - if you are killed by the blast, not only will you have wasted your time and effort, but the mine planter will be alerted to the fact that the mines are now missing, and will come to replace them.
Repair Guns are critically important to the game in several ways. Making the best possible use of them can make or break your chances at victory. They may not do damage, but they are not to be underestimated.