I'm playing XCOM: Enemy Unknown on easy at the moment and I think I'm about halfway through. I don't play strategy games often at all and Enemy Unknown has been fun so far, but man does the game like to kick my ass, kill my best people and remind me of my place sometimes.
Everything about the between-mission micromanagement and the menu driven combat just overwhelmed me at first but I stuck with it and the game opened up for me a lot, constantly learning new things. After the tutorial chapter (which I feel I took longer on than I should've) I was feeling confident in the squad I had built and my grasp of the game.
AND THEN... I think it was the first main story mission (the XCOM equivalent of ME2's Collector missions) that introduced me to, officially, my new most HATED enemy in any videogame. Even more than those fucking Cazadors from New Vegas. It's a creature that soaks up more damage than most enemies, can kill one of your soldiers pretty quickly and they fucking zombify immediately afterwards. It's frustrating because game played like tactical cover battles up to this point but these things (oh yeah and they ALWAYS come in groups of three) just about break the game when I encounter them because they act purely as ravagers, they just rush the hell out of you.
Apart from them I'm actually otherwise digging the progressively higher difficulty when it comes to other enemies and even the assholes I just mentioned (the game gave them the least convenient name possible, I don't know what they're called) aren't the impossible obstacle they used to be for me. I just couldn't imagine playing Enemy Unknown on any higher difficulty setting though, good thing I'm playing Saints Row 3 on the side when I need to blow off steam.