ECHO looks incredible and this speaks to the incredible power of the Unreal Engine. This is also one of the more unique approaches to game design using light and dark as a gameplay mechanic. Other games have used it for sure, but not in the same way that I can remember.
Darkness is much more than simply nighttime here. During the light-cycle (we’ll call it), enemies will learn from you and your actions. Maybe they won’t start out crossing the water or opening doors so they will be mildly contained. You still need to get to your objective, extract it, and get out. Once you open a door, the enemies (who look exactly like you) will also have the capacity to do the same. Crossing the water? Water is no longer a barrier to them. Shoot them with a gun? They will start shooting back. You’ve got to think of your actions before you use them because they will be used against you. Conversely, if you never open a door, the first time you close one of them, that will have them at a loss.
I chose stealth take-downs and that served me well. I had already taken one of my objectives and was well underway of grabbing the second when it took a turn for the worse. However, the dark-cycle happened at this point. Suddenly I was free to do as I pleased. Your actions aren’t copied while it’s dark. So after I gained attention grabbing the objective, I suddenly started to run and jump off of things and I got some good distance between myself and the bad “clones”. However, the dark-cycle doesn’t last very long and the light-cycle came back which resets all of the baddies including the ones I took out with my stealthy approach. Getting back wasn’t supposed to be easy in ECHO, but it was a lot of fun!