How to use some of the Weapons...

To plant a HE Charge, scroll through the Soldier's available weapons and select the HE Charge. Approach the desired target and press left click to place the charge.
NOTE: If doing an Objective, be sure to look for the destroy icon before placing the charge to ensure you have found the Objective.
Once the charge is attached to the target hold the Use Key ("Default F") to arm the charge. The charge will begin flashing and a timer bar will be visible bottom right of the HUD displaying how much time is remaining before detonation. Be sure to secure the location of your HE Charge once planted to ensure an enemy Constructor does not disarm your HE Charge. Once the HE Charge is about to explode clear the area to avoid being killed by its powerful blast.


GDF High Explosive Charge




Mining...

Engineers can only plant three mines at a time. Planting a new mine will remove the oldest mine. To place a mine select a mine from the weapon list and press left click to toss the mine in the desired location. Once the mine is placed it has to be armed with the repair tool. Arm the mine by approaching it until you see the arming icon and hold the Use Key ("Default F") or "Mouse 1" button until the mine is armed. Trip mines can be placed by using alt-fire however they can only be placed in certain locations like doorways and other small passageways


GDF Mine!




Hacking...


Only the GDF Covert Ops can hack Strogg deployables, disabling them for 60 seconds.The Covert Ops can hack objectives and Strogg deployables by approaching the target and holding the Use Key ("Default F") when the hack icon appears. Continue to hold the Use Key (Default F) until the target is fully hacked. Deployables can only be hacked temporarily before they are reactivated.
Since 1.4, deployables can now be hacked twice which will reduce them to half health. However, this also removes the 60 second time that the deployable remains hacked. Retrieved from.


GDF Hacking Tool!