This post is more than likely going to be poorly constructed waffle, but I am currently going through the game as previously mentioned on the hardest setting. Tactics are vital, and using all the tools in your arsenal as designed is critical. I am going to discuss in the following post, a number of Stealth tactics that I have found to be useful:
Disclaimer: Some of the tactics below are not for everyone and some of the strategies may be arguable, but this is just my take on the game and tactics I find work for me ;)
Suit Mechanics:
Firstly, lets talk about the stealth mode. In stealth mode, you are invisible, and your footsteps are muffled. Opponents will still detect you if you move a lot near them, especially if your directly in front of them. I would recommend one of the first Suit Upgrades you get be the Stealth Enhancer, as the duration of Stealth mode is extended significantly.
A few tips for stealth mode:
1) DONT USE ALL YOUR ENERGY. If you run out of energy, you are visible. If your visible, you dont have energy to enhance your armour. On diffcult modes, without quick reflexes and a good aim - this usually means a reload screen is imminent.
2) Locate cover. Situational Awareness is key - if you have played through on an easier setting before hand, this is all the easier. Try to identify where your enemies are, (Battlescape view and tagging enemies makes this a little easier, but dont rely on tagging all the enemies, most arrive on the battlefield after you have commenced battle and the corpses pile up.) and make sure you can find some cover to try to pick them off with silenced attacks, or "pop-up attacks".
3) Relocate. If you reveal yourself and are spotted, or a body lies near your cover, the enemy will come investigate or commence fire on the general area. Unless your baiting the enemy to come to you for melee or point blank take downs, you might want to pop out of cover and relocate.
Silencers:
Silencers are extremely useful for a stealth run, though not essential depending on the approach you wish to take, especially if your using a gun that is powerful enough to perform an effective "Pop-Up Attack" as discussed later. With a silencer, you can fire off single rounds from most guns whilst maintaining stealth. This is great for peeling health off Ceph by shooting them in the Jelly, or for headshotting human opponents.
The best weapon for this is the Nova as you can get off a half a dozen shots and move back into cover to regenerate your energy. Later on, the Hammer or a silenced Scarab in single-shot mode prove good substitutes. I would bypass the hammer in favour of the Scarab since the Reflex scope or Ranged scope make for very easy targeting of opponents that are further afield. If you screw up - you can tap full auto mode and try to finish the target off.
Pop-Up Attack
To perform a pop up attack you simply uncloak and fire of the shot or burst, then re-cloak. You momentarily give your position away to anyone looking in your direction, so it is likely you will need to relocate after performing this attack a few times. If you have a silencer, you will have more time and can effectively kill a majority of the targets in the field like this. Without a silencer, I find the most effective way to use this is something more powerful, in single fire mode (or in burst if you feel the need to ensure that target is dead.). Uncloak - head shot/burst - recloak. if your quick and have the stealth upgrade, your visible for such a short period of time your often un-noticed, save the sound of un-silenced weapons giving you away.
Sniping
With a silencer and willingness to relocate - the G1 sniper rifle can be put to awesome effect. Its best to perform a pop-up attack, or you are left with your nuts swinging in the breeze when half the map turn and start blasting at you. A silencer will buy you some time before the enemy can locate you. Plan your targets, and enjoy! One of my favourite past times is finding a good spot to empty my ammo supply from. Without a silencer it is still possible, but expect to have to relocate often.
Relocation
Fairly simple and self explanatory: When your position is compromised, move to another location! Ideally with some cover and your line of site blocked to recharge your energy when you get there.
Advanced Relocation
Revealing your positon to the enemy (preferrably by de-cloaking and taking out an enemy of two with some pop-up shots) can be a good strategy, and is one of my most oft-used tactics. The enemy will start firing on your position, and in the case of the Ceph, will converge on that position. You will be under spray-and-pray fire when you get up to move, but dont worry as unless the enemy strip your energy, they cant see you - just keep moving. By relocating at this point it is possible to find some isolated targets, or flank the enemy forces and with good use of Silenced stealth kills or pop up attacks, you can eliminate most/all of the enemy forces. I particularly like placing some C4 in the baited area or lobbing some grenades from my new spot once the enemy have gotten to my last known position. Blissful giblets flying through the air is a sign of success! :-)
Run & Hide
If your caught out in the open - or don't have enough energy to get to cover - don't be afraid to drop cloak in favour of shields or a momentary recharge and gun and run. If you can take out some targets in the few seconds whilst waiting get some energy back - you will want to use the regenrated energy to activate your enchanced armour and sprint to some cover... (that is unless you get enough to cloak relocate) then quickly regenerate your energy and attempt to relocate. This is very similar to advanced relocation in that your going to be under fire, so be quick!
Silent Kill
If you can find a target on its own, or flank a group and none have you in their field of view, you can perform a silent kill. As an alternative, you can do the grab&jab mentioned below. A silent kill works on any target without a shield, or that is not massive. (Heavies, Pingers and shielded commanders I think are the only ones immune to this.)
Grab and jab
This is actually my preferred version of a silent kill. You grab the target whilst cloaked. This works wonders if the target is advancing on your position, or knows you are there and is running at you. (Im looking at You Ceph assault troops!) You simply grab the target, and can then perform a silent Kill. This method drops you out of cloak like a silent kill, but only for the moment you perform the grab. The time exposed is less than that of a stealth kill, and you can move as soon as you have grabbed the target, just in case someone DOES see you exposed. If behind cover, you can grab the target from the cover your hiding behind as it comes to investigate, and execute it out of sight of its comrades.
I found this tactic to great effect on one section of the game - a large area quite early on after meeting the Ceph - and there are some dozen or so targets. On the first run through I shot them all, and made it through with 8 scarab bullets left... This time round I used a single clip. I shot from the balcony and the target would then come over to investigate where the shot came from. I stood by the side of the doorway and grabbed the target as it moved through the door. In some cases 2 or 3 came to investigate and I managed to pluck and stab them as they came through the doorway. By the end of it all I had a bloody pile of rotten Carcasses by the side of the door and did not take a single hit.
A few donts:
1) As mentioned before - DONT run out of energy. When the crap hits the fan you will need to quickly hide and relocate, or will need to activate your enhanced armour lest you become goo on someones boot.
2) Dont be afraid of melee... I find a majority of my killing blows come from close combat, or stealth kills.
3) Dont fire an unsilenced weapon stealthed. It strips all your energy and your life expectancy is greatly reduced...
4) Dont fight from the Open - unless there is somewhere to hide behind, sheer weight of fire will kill you fast on the higher difficulties, or will force you into enhanced armour mode, which on a stealth run is a last resort. You dont want to be caught in a gunfight, you want to know where the enemy are, and for them to NOT know where you are.
If you have anything to add, dont hesitate to comment below and the "guide" can be amended.
