It's a good game, so even though this won't sound like me singing it's praises I need to get that out of the way. The multiple ways of handling situations really shines for me, it's the execution I find falling short. For some reason I decided to do my first time through on the hardest difficulty, aside from some HUGE issues I have with the cover system it hasn't been a challenge yet, aside from the first boss since my character is stealth based.
Now my honest opinion on some things. I think the story is fairly smart and engaging, it's a good change from the norm. I find the voice acting kills things sometimes though. The voice acting isn't bad by any means, but it is very mediocre and the protagonist's voice makes me wanna hit something after hearing him talk for 5 seconds.
The AI isn't all that great, even on the hardest difficulty you can pick off entire rooms with relative ease, it took three missions for me to even get spotted and that was because I wanted to change it up and run and gun. I think this revolves around the energy system, which I despise, and the imbalance of takedowns in this game.
Shooting isn't all that great, but it's not like I expected gunplay to be all that great in this game. The cover system makes me wanna scream sometimes, holding a button to stay in cover really bothers me, it seems very unnecessary.
TL

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I love the atmosphere and the story is quite engaging. The multiple path approach is great. The gunplay is mediocre as is the AI. Some of the systems don't seem all that well thought out. Inventory reminds me of RE4, which is a good thing. All in all it's a good game, reminds me of a more polished Alpha Protocol, if you want a rating 7.75/10. Definitely worth playing.
Edit: New score. 6.5/10. HUD just disappeared at around 15 hour mark. Thought it was part of the game at first. It isn't. It's a glitch. It's quite game-breaking. I'm not restarting. I'm finishing without my HUD. Then I'm gonna return it out of principle.