As I promised to Vulong, here are some strategies and tips how I play OpenRA.
Check the hotkeys for building and training your optimal build order so you save time.
CTRL: Force attack. With this you can attack the ground or anything that would not give you an attack option (like your own units).
ALT: Force movement. You can use this to crush infantry with tanks.
SHIFT: Queue orders. Hold it down so you chain orders together. For example: pick up this crate and move back. Go there so you do not go into enemy defenses and attack from there. It is good to counter horrible pathfinding.
X: Scatter, you can counter the previous attempt with this or you can move your group of units further from each other (so they do not explode in a chain reaction).
A: Attack move. The unit moves and attacks everything in its path.
S: Stop, cancel last command (like force attack of the ground without moving).
F: Unload/Deploy or return Aircrafts to the base.
Z: Cycle selected units through HoldFire / ReturnFire / AttackAnything / Defende stances
V: Sell building
B: Power down bulding
N: Repair building
TAB: Cycles production tab (SHIFT+TAB is the reverse).
Backspace: Center sceen around MCV.
Spacebar: Center screen around last event (base under attack).
Middle mouse button: Drag the screen fast.
Always consider your power level when placing a new building, especially if it drains a lot, like defenses. Do not build your powerplants too close together because a single nuke can take them out.
Build your refinery as close as possible to the ore field. You lose time and money if the truck needs to drive a lot. After it is depleted sell the building and give your harvesters a new job. It is wise to have more refinery for a good economy and you should build additional harvesters as well.
Try to expand as soon as possible. Even before you are able to build a second MCV, you can undeploy your main one and move it somewhere else. Do not send it too far because you can only build in its vicinity and you can not make buildings while you move it. It is wise to have more construction yards since now a single nuke can destroy one. For this you need a war factory and a service depot.
Allies have the tricks and Soviets have the raw firepower and strong defenses. When played in teams combine the two factions and mix the technologies.
Go for the rock paper scissors tactics.
Do not throw every unit blindly into the enemy force or defense line. Divide them to groups and use them what they are strong against. Also do not always move different units in a single group because they have different speed so the tanks are going to leave the infantry behind.
You obviously know how to click on a single unit and that you can hold down the mouse button to select more. But you can also double click on a unit to select every similar one on the screen add to your existing selection with holding down SHIFT. You can use this with group selects.
Ground units in most cases by default are to set AttackAnything
Submarines are set to HoldFire
Air units do not support stances
You can order your units into groups. To do this select them and press CTRL+# (# stands for a number from 0-9). From now on you can select them by just pressing the number. Double tapping it makes your screen centered around them.
I usually use 1 for scouts in early game and 2 for my optional rush team. It is a good idea to use a different number for a defense team and for naval and airborne units.
Since the rebalance they are more useful in great numbers. A big army can take out a mammoth tank in no time. Use them to scout in early game. In the early game build rifleman only, because you do not need to counter tanks and planes yet. The two most used units are the rifleman and rocket soldiers. The later is great against tanks and they can take down planes. Do not bother with other offensive infantry like tesla or flamethrower since they are expensive and easy to counter.
You no longer lose them after you captured a building. Instead they need to stand there for a while. You can repair destroyed bridges with them. A good defense against them is a simple wall. You can move them quickly in a chinook or APC with other special units. You can use them to instantly repair your and your team mates buildings.
They are great siege weapons but also good for defense. Place them behind a natural barrier or build a wall and order them to guard the border of your expense. Do not try to defend the inner base with them because they can damage your buildings and units. Their attack is slow so fast enemies can outrun them. This is why you need to keep them behind walls or your faster units. Do not place them close together because if one dies they explode in a chain reaction and take out the others. This also goes for grenadier infantry. If you suspect enemies in the shroud you can force attack the ground with CTRL. Use them to take out defenses from a nice distance.
[Taking out enemy defenses]
Use planes or artillery to take out tesla coils or sabotage their powerplants because they need a lot of energy. AA and tesla needs energy, pillboxes turrets and flame turrets do not. Attack AA with ground units, preferably from a distance if there are ground defenses nearby.
The only good way to counter a naval army is to have your own. Using aircrafts to guard coastlines can be good as a warning system but they are useless against subs if they are microd well. They are obviously limited to water but players tend not to defend their coast lines and put power plants and key buildings there to keep them safe from ground units. Use this to your advantage and use bombard them from the water.
Aircrafts need to recharge their ammo and you need to micro them carefully, but they are great tools. Yaks and Hinds in early game are great for scouting. They are strong against infantry but weak against tanks and most buildings. The only building they are really good against are power plants. Use them to take out grouped enemy infantry and to expand your ground units vision. Migs and Longbows are good against buildings and harvesters. Build more of them and send them to attack a key building or harass harvesters. These units circle aroung in one place if ordered somewhere on the map, you can leave them somewhere as you prepare for an attack but do not forget about them because they are fragile and expensive. When ordered to attack they fly in a straight line to release their missiles, go throught the target and turn back for another attack. This can be dangerous if the enemy has anti air units or defense. Lucky for you their vision is better than the range of those and if you order them back as soon as their released their missiles you can move back a bit and do another attack run without being in the range. You can repair them on a service depo.
Build AA defenses if you suspect your enemies to attack with aiborne units, but do not put them close together. Cover your base with it. It is also good to withold the placement of the building until they attack. Rocket infantry are great against planes but they are slow. Place them in your base and order them to defend so they will not chase the planes.
They are powerful siege weapons and they can shoot air targets but they are slow as hell and relatively fragile if faced with an army and because they are expensive you will not have enough of them in this case. So do not order them to the frontlines, only after you broke the defenses. Their are ideal to use with chrono sphere and iron curtain.