In The Surge 2 not every enemy is aware of your presence, which means you can often backstab them for a deadly advantage if you are sneaky. You may as well take advantage of your foes sleeping on the job.
Approach your enemies slowly and wait for the red marker.
So long as an enemy has their back turned and is unaware of your existence you can backstab them. Just slowly walk up to them (lightly pressing the left stick or the Q key), target them, and get close enough until a red marker appears around their targeting icon. Tap the RB or left mouse to trigger the attack (this only works with horizontal attacks). The enemy will only be stunned for a few seconds, but follow-up with two to three additional attacks before they retaliate, dealing heavy damage to them in the process.
And that’s all there is to it. Remember to wait for the red marker, otherwise you’ll do a standard attack. Now go stealth murder some goons, you silent exo-suit wearing delinquents.