Many people seem to be having trouble with the final switch puzzle towards the end. It makes sense, the clue isn't quite easy to spot at first but I guarantee a few of you might slap yourselfs on the forehead after I explain this here.

So, to begin, once you go down the "pepsi" elevator and into the secret EDF base, kill the aliens that are waiting for you and take a look around the room...

https://steamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=1490530258

Let's take a closer look...

https://steamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=1490530357

If you press the "interact" key, this pops up...

https://steamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=1490530464

Now see? It wasn't that hard! The intention of placing that note in the starting office, the one that talks about the invasion, was to prepare the player for that exact scenario! I see not many picked up on it. Oh well, just helps me grow as a mapper to see what players react and don't react to. Keep on gaming guys, and I hope you're enjoying the maps thus far!