***SPOILERS ALERT!!!!***
OK, I just got this achievement so here the guide it will take me some time to complete the guide but please bear with me and I will take suggestions and tips as well, thanks.
I have confirmed that you cannot play through the game on "Easy" and then change the difficulty setting to "Unleashed" before you finish the final boss, this will NOT unlock the achievement. Each level must be STARTED on "Unleashed" mode and finished for this achievement to unlock.
(I beat the game on "Unleashed", waited for the credits and my achievement did not pop up... I looked at my level select and noticed the first level was not beat on unleashed, I must have changed the difficulty form Easy to "Unleashed" after I beat the game once.)
"Unleashed" mode can only be unlocked by finishing the game on ANY difficulty. And if you did as I did, start the game on "Easy" then beat the game on "Unleashed" all lower difficulties will also unlock. The achievement should pop right when the FINAL cut-scene starts after you choose which side (Light or Dark).
The differences on "Unleashed": #1 Enemies do more damage, #2 You receive less health for each enemy you kill, #3 Your Force Bar takes longer to replenish, #4 You have no Health Regeneration, NONE whatsoever. #5 Your Force Bar depletes faster. I think that is all the differences between the difficulty settings.
Boss #1: Space ship. (forgot the name of it :P)
This guy isn't very hard at all even on hardest difficulty. When hes using his lasers just hide behind the barricades. Only come out when he shoots one missile at a time, rebound these single missile attacks either by using Force Grip or your parry move (press the X button 1 second before the missile hits you). When he does the 4 missile attack simply hide behind the barricades or move out of the way. Press the button combinations when prompted. Rinse and Repeat and you have him.
Boss #2: Gorog
This guy is the 2nd toughest boss in the game I think.
Phase 1 attacks:
Hand Swipe: Double jump and mid-air dash out of the way.
Fist Pound: Dash out of the way.
Palm Pound: This one is quick and has much more range than the Fist Pound. Just wait until the last second and Super Dash out of the way (Super Dash is performed by dashing and immediately performing the force push maneuver after you dash, it give you a little extra of a dash and knocks down any enemies in your direct path.).
Breath Attack: Block.
Double Ground Pound: Lightning 1 hand, it will take just slightly over a full bar of lightning if your force bar is 100% maxed out. Follow through with the button sequence, then rinse and repeat for the 2nd hand.
Extended Breath Attack: Block until his face is turned the other way, then lightning him. You'll need to do this until all of his green bar is gone.
Phase 2: He is quicker in phase too and there are stormtroopers every now and again as well.
Triple Hand-Stomp: Wait till he smashes twice then dash out of the way before his 3rd smash.
Force Push seems to be most effective as it uses very little force power and its does the most damage. You'll want to switch to lightsaber attacks when hes hanging form the top though.
Phase 3: Compared to the 1st 2 phases this one is a joke, simply dodge upwards and use force push to break through the objects that are incoming. Also use the Dash maneuver to speed this phase up, when you get closer try to upwards dodge and force lightning him. once you get even close just use Lightsaber Throws. This phase isn't hard at all. Good luck. I think I spent a little over an hour on this dude my 1st time through on "Unleashed" difficulty.
Boss 3: Large Spider thingy (Steve)
This dude himself isn't tough- its all the little guys around him. TOP PRIORITY- take out the "Disappearing Siths" 1st, as they are the most formidable. To do this effectively just Force lightning them once the appear near you, they will be stunned now, so smash in a lightsaber combo or 2 and they are done for. Also anytime you see a "blinky mini spider" coming up on you then Force Repulse him, no need to charge it up. Use the explode Barrels nearby to Force Grip and throw at the "Large Spider", they do massive amounts of damage. Remember to keep dashing this whole fight and try to fight away from the "Large Spider", only once you've taken out enough enemies or received enough health form killing lots of small spiders, then you should go and attack the big spider. At one point the "Large Spider" will get his shields up, then you need to place all 4 power converters back into their slots (remember to Force Repulse all the "blinky mini spiders" before doing this on each power converter). Once that is done, attack him some more then you will be able to ride him. This is the easy part- simply use your missile and laser attacks to kill all the "human size spiders" around, (I think there is 3 or 4 of them.), then move the "Large Spider" into the large beam. End of fight. The tough thing about this fight is all the dudes that are attacking you at once, rather than 1 dude. Best of Luck! This was the hardest fight for me.
More to come soon.