Bodycount

This achievement is for beating the game on hard mode. While it's not the most difficult in the world, it can be very annoying/frustrating so here's a few tips that helped me get through the game without too much trouble.

1) The Tavor/Kaluka combo ends up being perfect in almost all situations. Kaluka is great at essentially any distance, especially close/mid, and the Tavor is fantastic at long ranges. Switching between the two as you go along should help quite a bit. For the levels you don't have the Kaluka, I'd say use the G36.

2) After I got about halfway through the game I was sick of dying to things that didn't make any sense, so I started running through the levels. The AI isn't very smart when you're quickly moving, so it's fairly easy to learn the spawn points and then just use the safest path to run by all the enemies. You get an ability that allows you to not take damage, and using this to run through tougher areas can make some of the levels a cake walk. Every waypoint is a checkpoint.

3) If running through the levels isn't working, just use it to your advantage. In most cases you can get by a good amount of the enemies and find a corner to use mines/corner peeking to kill all of the enemies if need be.

4) Always keep an eye on your grenade total, because using the Impact Grenades (tapping RB twice) will be a life saver from beginning to end.

FINAL BOSS:
This is probably the toughest part of the game at first glance, but there are many advantages you can use to make it incredibly easy. First, make sure your weapons are completely loaded. When the boss lands next to you immediately run straight ahead and up the stairs in front of you. Stop at the first pillar and lean either left or right and unload a clip of the Kaluka at her. A majority of the time she will fly closer to your position and land in the hallway next to you. All you need to do is retreat to the stairs and shoot at her until you're taking damage then crouch so she can't see you. You'll be close enough to collect the intel she drops, which is integral to winning the fight.

Once your intel is full you'll be prompted to use the Pulse ability. Once you've dispatched the regular enemies, use the pulse technique. This will make the boss fly away and you'll be told to get to the SAM. Avoid the airstrikes and activate the SAM to do a bit of damage and get a checkpoint.

You can repeat the above steps until you activate the SAM a second time and then you can try the same strategy, but I found it easier to use the upper part of the level for the last part. Try to use the stairs at the very back and get her to fly to the very top. Generally she will be in wide open space and you'll have various cover around you. Fill your intel, get to the SAM, and the fight should be won!

Simply beat the game on hard.

This game is not too bad on a hard playthrough. Takes about 8hrs or so. The most difficult parts are probably going to be the Target bases, only because their guys have great guns/armour.

Some general tips:

1) I found the best weapon combo to be the G36/Tavor or the Kaluga/G36. On hard, the enemies do quite a bit of damage, so you want to stay away from them as much as possible. The Tavor is good for headshots, and the G36 is an excellent all-rounder. Once you get the Kaluga, don't look back (except when they take it from you for a couple stages). It shreds pretty much everything. The pistols/shotgun are worthless. If you prefer the Minimi, take it instead, but I found accuracy to be the deciding factor. The energy shotgun/rocket launcher can be useful in large arenas, but the slow reload speed and poor collision detection (thinking you did not lean far enough out of cover) ruined it for me.

2) There are very few infispawns, and they are only 1/2 guys at a time. Very manageable.

3) If you can spare them, explosive bullets shred heavies, as does the Kaluga. It is not as effective against Target elites through, so impact grenades work well, as does the energy shotgun/launcher (if you are using it, I just shot them a lot with the Kaluga)

4) In large arenas, a good tactic is simply to kite the opposition. The AI is very poor at following you quickly, so killing a couple from range, and sprinting to the other side to repeat works very well. This is eespecially useful in the datacore arena near the end.

5) Learn mine placement. After dying in a few arenas, you know the spawn pattern and can place mines accordingly, killing a lot of enemies quickly.

6) Be careful with the doors in Target bases - on two occasions I had to restart the stage because I moved through an open door, retreated when I got shot, had the door close and lock in front of me (as it was designed to keep you in the room).

7) EDIT: As mentioned in the comments, the beat the last boss, you need to damage it (with guns/mines/grenades), upon which it drops intel. After getting enough intel for the pulse wave, hit the boss with it, then dodge airstrikes on your way to activate the SAM site at the rear of the arena (via the computer panel on the back of it). This nets you a checkpoint as well. Repeat twice more to win. I found the Kaluga combined with mines and an impact grenade or two the best way to damage the boss, as it will shred you up close with SMG's if you let it.

8) Keep at it. As I said above - spawn positions are static and the enemies fairly dumb. Good luck!

If anyone has any other tips, please put them in the comments and I'll add them. Thanks!

Some bits on this game is tricky one of the main problems is the game auto saves in stupid location like in middle of a fight. I also got stuck on certain objectives and kept die'in if you have same problem try this walkthough out that I used. Its on Medium Difficulty but the techniques still work for hard.