Deus Ex: Human Revolution - Director's Cut

I was told by my boss that I could go in lethal or non-lethal. I chose non-lethal, because they weren't described as anything other than "purists". Turns out they are fully kitted, armored mercs. You cant reload and choose lethal and give yourself a fair fight. Overall the opening 45 minutes was grating. I don't want to have to start a new game and play again. I have restarted other games 9 or more hours in, because they're fun to play and I messed something up for myself. This game gives me nothing in its opening 45 to even want to replay that. I am constantly having lagging. My GPU percentage is at 34% and I have 250-400 FPS. So...

Beautiful game, I wasn't liking it in the beginning because I was confused with how to properly play it so I kept dying, then I realized I was just making life hard for me, because there are different ways to go about a mission, you just need to explore and even chat with the NPCs to get clues. I liked the game a lot. I played it non-stop. I can't wait to try the second one.