Since this thread is specifically about MIND games, the most devastating example was a game I played last year that resulted in my ally thinking I was betraying him, making him turn on me, having an outburst and DELETING SUBTERFUGE - never to play again.
It started with a 1st game player building a mine on day one. My ally took the bait (pretty sure it was bait) and attacked. Problem was there was a three way alliance (we think) that fought back. Then I got attacked by a fourth player, so before we knew it we were tied up fighting different opponents. Not an ideal scenario.
So my ally reached out to the biggest player about a deal. He said he couldn't make that deal because he "reported to purple (the noob)". Didn't make much sense. Sounded like BS. Then they offered a peace deal *if* my ally agreed not to build a mine - and hence lose. He obviously rejected it.
There was more Stuff that had us both wondering who the hell was running a campaign of BS; I admit I thought my ally might have been playing me. But eventually all the BS finally erupted into an argument between myself and my ally - who accused me of working with the enemy because I hadn't attacked them as he thought I could -- truth was I was tied up with the fourth player. I admit I probably overreacted by impulsively revoking funding from my ally - with intentions to fund him again after he cooled off - but it was too late. My timing couldn't have been worse (unknown to me at that time) and is seemed to confirm I was working with the enemy. Mentally I think he snapped. He started gifting and helping the fourth player I was fighting.
All the while I was pleading my loyalty, refusing to attack him back, and warning him the fourth player could not be trusted. Eventually the fourth player eliminated him - like I said,not to be trusted. My ally said some blunt words to me and public chat, and that he was deleting subterfuge.
He hasn't played any games since. Jard if you ever read this, I didn't betray you dude, and you need to play another game.
Ironically his elimination forced me to reach out to my enemy, and we eliminated the fourth player with 40min to spare -- despite sending his queen and three princesses in all directions of the map. It was a brilliant coordinated effort ... With my enemy?!
I still to this day dont understand all the details of what happened, but there was clearly a psychological warfare strategy in place that tore our alliance apart. And it was devastating in its brilliance and results.
"I work for the company. But don't let that fool you, I'm really an okay guy."