First let me tell you about SAO games and order.
1 Sword Art Online: Infinity Moment (PSP - Aincard only)
Sword Art Online: Hollow Fragment (PSV + Aincard + Hollow)
Sword Art Online Re: Hollow Fragment (PS4/PC AIncard + Hollow + patch with Garden)
2 Sword Art Online: Lost Song
3 Sword Art Online: Hollow Realization
3.5 Accel World Vs. Sword Art Online (its spin off this is why as 3.5.)
4 Sword Art Online: Gun Gale Online
5 Sword Art Online: Alicization Lycoris

There are also games on phone.

Beacouse Hollow Fragment is third version of the same game we have here some differences.

• New translation - this is why all guides for Re version are wrong. All places, items and more have new names
  
• Patch with garden is now part of game so you must do it to have all achievements and with this there are some changes with numbers like fe. max LV
  
• OSS is now weaker. There is no extra bonus for more skills in chain, but still it's best build if you are good with OSS
  
• You don't need to record skills for OSS. Now you can use all skill you want
  
• Skills have now Cooldown, bud don't use SP
  
• Some changes in dating. Now second option isn't always best
  
• Def now isn't 0-1 for you. In PSV you had def or you have 0 def when monster has better attack than your def. This is why all char guides says that def is unless stat. Now you def will always help you to decrease damage on you
  
• You can do all Hollow quests in multi (without dlcs), so is easier to do implements

Maybe there are more changes but i don't know them.

In this game you have 2 main plots:

• Aincard with new char: Strea. Finishing it is end of game
  
• Hollow with main char: Philia. Finishing it you have credits but isn't end of game. Also Hollow won't reset in new game+

Aincard story - cannot miss:

• Beater
  Complete tutorial (it's in Hollow but you start there and cannot return before)
  
  
• Defeat The Ghastlygaze
  Defeat the boss in floor 76
  
  
• Defeat The Crystalize Claw
  Defeat the boss in floor 77
  
  
• Defeat The Horn of Madness
  Defeat the boss in floor 78
  
  
• Defeat The Tempest of Trihead
  Defeat the boss in floor 79
  
  
• Defeat The Guilty Scythe
  Defeat the boss in floor 80
  
  
• Defeat The Knight of Darkness
  Defeat the boss in floor 81
  
  
• Defeat The Legacy of Grand
  Defeat the boss in floor 82
  
  
• Defeat The Horn of Furious
  Defeat the boss in floor 83
  
  
• Defeat The Queen of Ant
  Defeat the boss in floor 84
  
  
• Defeat The Maelstrom of Trihead
  Defeat the boss in floor 85
  
  
• Defeat The King of Skeleton
  Defeat the boss in floor 86
  
  
• Defeat The Radiance Eater
  Defeat the boss in floor 87
  
  
• Defeat The Rebellious Eyes
  Defeat the boss in floor 88
  
  
• Defeat The Murderer Fang
  Defeat the boss in floor 89
  
  
• Defeat The Ruler of Blade
  Defeat the boss in floor 90
  
  
• Defeat The Absolute Gazer
  Defeat the boss in floor 91
  
  
• Defeat The Chaos Dragon
  Defeat the boss in floor 92
  
  
• Defeat The Lava Creeper
  Defeat the boss in floor 93
  
  
• Defeat The Knight of Blazing
  Defeat the boss in floor 94
  
  
• Defeat The Genocide Eyes
  Defeat the boss in floor 95
  
  
• Defeat The Slaughter Fang
  Defeat the boss in floor 96
  
  
• Defeat The Emperor of Death
  Defeat the boss in floor 97
  
  
• Defeat The Kaiser Dragon
  Defeat the boss in floor 98
  
  
• Rulers of Hades
  Defeat the boss in floor 99
  
  
• Congratulations, Kirito
  Defeat the final boss in floor 100

Hollow story - cannot miss:

• Defeat the boss of the Sea of Trees Area
  
  
• Defeat the boss of the Floating Ruins Area
  
  
• Defeat the boss of the Great Void Area
  
  
• Defeat the boss of the Control Area
  
  
• Wow...
  Defeat the boss
  
  
• Shadow
  Defeat the finall boss

Aincard story - you can miss them, if do, play new game+

• Beta Tester
  Get every Last Attacking Bonus
  
  Every floor boss has Last Attacking Bonus drop. So you will got drop for killing boss. Its from floor 76-99. On floor 100 you also can have LA bonus but there is no drop for this so only until 99 works. I'm not sure if you can sell it so better inserd all in chest. You can also find these items as drop but it won't count.
  
  On 99 there are more bosses but i think only last one count.
  
  If you fail to got bonus item just ALT+F4 on congratulations screen and you won't save progress. Then you can fight him again.
  
  List of LA (i hope in good order bc i have only screen schots)
  
  • 76 Dual Gloves
    
  • 77 Seeker's Plate
    
  • 78 Cross Jacket
    
  • 79 Dual Greaves
    
  • 80 Cross Boots
    
  • 81 Duel Vest
    
  • 82 Miner's Gear
    
  • 83 Chaos Greaves
    
  • 84 Undercover Agent Coat
    
  • 85 Chaos Bracers
    
  • 86 Elven Garb
    
  • 87 Chaos Armor
    
  • 88 Dark Repulsor
    
  • 89 Elcuidator
    
  • 90 Rampant Light
    
  • 91 Finsterglanz
    
  • 92 Valkyrie Mail
    
  • 93 Order Bracers
    
  • 94 Shadoweater Boots
    
  • 95 Order Boots
    
  • 96 Shadoweater Suit
    
  • 97 Order Garb
    
  • 98 Fatal Garb
    
  • 99 Sleipnir Ring
  
  
• Not on my watch!
  Complete the game without any one of the Assault Team dying
  The same, if someone die just ALT+F4 on congratulations screen. 140 level should be safe for you. And you can also train your team after every flood, but it's boring
  
  
• Absolute Sword
  Defeat hidden final boss.
  When you end game you will see option yes/no. Choose yes to go for more fight. Now you must defeat optional boss, by droping his hp to yellow
  
  
• Don't cheat, daddy
  Increase Affinity level to 5 (max) for:
  
  • Asuna
    
  • Lisbeth
    
  • Silica
    
  • Leafa
    
  • Sinon
    
  • Philia
    
  • Strea
  
  
• Memories
  Unlock all photos in gallery. To do this you must do:
  
  • On every floor do all events [!]. Check event list
    
  • Do all bed scenes with girls from Don't cheat, daddy
    
  • Story ones from Aincard and Hollow
    
  • Do heroine quests in Hollow, then go to La Ulquera Gradens with all girls (must have level 5 Affinity). Plus do this also with Bonus Hollow char 2 (i will write later) and Argo.
    
  • Find bonus hollow char
    
  • See all ending: kill last boss with all girls you can choose to do them. After final boss and ending you can continue and you will go for last save before boss.
    
    • Asuna
      
    • Lisbeth
      
    • Silica
      
    • Leafa
      
    • Sinon
      
    • Philia
      
    • Strea
      
    • Yui
      
    • Philia
  
  Important
  
  • Complete Hollow Fragment storyline before floor 86 (i had it on 88 so I'm not sure). You must have Philia unlocked or you will get CG without Philia. With Philia you will get 2 at once
    
  • Get rank 5 with Strea before floor 90
    
  • On floor 100 you must first kill boss without helping event. Just don't take Yui to Hollow in first run. Then after game choose continue and finish that event

Other

• Complete debug
  Complete more Hollow Missions than required
  On psv it was 80 hollow missions, but now i think it's 100 hollow missions. And there must be different, so the same mission done couple of time doesn't count!
  
  
• High-rank test player
  Complete more Implement Element Researches than required
  Complete 100 implements (out of 114 total). it will count only durring hollow mission. First from administrator panel you must choose which implement you will do, then go for hollow mission and do what you must do. You can do it in more than one mission but you cannot change it before over or you will loose all progresion. Hollow missions are missions with circle and have levels from 1 to 3 for every area. If area has level 2, then there will be missions 1-2, if 3 1-3. That's progress bar shrinks when you don't do missions in this area. Level 3 are boss fights and are hard.
  
  
• Lisbeth Smith Shop's most loyal customer!
  Upgrade weapons 200 times
  Do it with items you want to sell. Go to her shop and do it with level 1 upgrade only. When you do str upgrade then you will choose anything else than str it will change from str on this new one. It cost less and every level has less chances to succes. You can do her all Aincard events to have her increase chance. Also there are 3 type of gems that will increase chances but... forger about them. You can find them only in 200 floor dungeon at about 150+ floor or after fight with very hard optional boss. So mostly to have weapon to kill hard boss you must... first kill him:D
  
  
• MMOs that use a level system are unfair that way
  Kirito reaches at least level 150
  This is from PSV, here you must do 200 level.
  
  • max level is 300
    
  • Aincard's max level normal monster is about 140
    
  • Hollow's max level normal monster is about 145
    
  • Garden area in Hollow's has high level area where monster can be from 160-210
    
  • Advance dungeon with 200 floor has increase monster level until 300 (insane)
    
  • Every new game+ is about +10/20 level for monsters
    
  • Multiplayer has on normal +20 level, on hard +80 and on dead game +160
  So you won't have 200 level without grinding. For more exp from one kill you can use:
  
  • Level 1 exp potion (random chest drop)
    
  • Level 2 exp potion (random chest drop)
    
  • Exp skill (must unlock first, but you can do it at start of game if you have points)
    
  • Weapon and armor (ark) with exp mod
  
  
• Billionaire
  Save 100 million Col
  
  
• Thank you for playing
  Complete the game after 100 hours of playing time
  
  
• Flash
  Raise your bond with Asuna to the max level
  
  
• Beast Tamer
  Raise your bond with Silica to the max level
  
  
• Master Macer
  Raise your bond with Lisbeth to the max level
  
  
• Fairy
  Raise your bond with Leafa to the max level
  
  
• Sniper
  Raise your bond with Sinon to the max level
  
  
• Treasure Hunter
  Raise your bond with Philia to the max level
  
  
• Teaming up is not that bad
  Total multiplayer time exceeds 20 hours
  
  
• This game is not for fun
  In a multiplayer game, defeat at least 100 level HNM creatures

Road map for achievements

• Tutorial
  
  
• If you want have Philia scenecs in all group events in first play then finish Hollow story before door to first boss on 76 level of Aincard
  
  
• If not, finish Hollow story before 86/88 floor (i'm not sure, saw somewhere that it's 86, but on my second play it was on 88). After boss on next floor you have automatic grade S food event which has 2 versions: with and without Philia. And you need it for Memory achievement. With Philia you will get 2 CGs, without only 1
  
  
• Try changing girls when they hit level 5 intimidate level. First make Strea, beacouse she will not accesable on about 95. Plus i read that you need her on level 5 before 90 level for event with CG. Also you can work for girl's armors.
  
  
• Before next floor level do all events
  
  
• Finish Aincard story but on level 100 don't do blue event with Yui. You can talk with her to start it but don't take her to Hollow!
  
  
• After last boss press yes for hidden boss fight - achievement and CG
  
  
• Press continue and start final battle with every girl on partner list
  
  
• If you want make Aincard easier you can do implement achievement after Hollow story, but leave all NMS kills for multi. Also girl's leveling and implements are easier on multi. For easier/grinding implements try them on high level areas to do 200 level faster
  
  
• Memory achievement will unlock if you enter album after last CGs

You need 78 CGs for this. And it's different for PSV version of game.
Here you have link with photos but I'm warning about spoilrers:
https://www.playstationtrophies.org/forum/sword-art-online-re-hollow-fragment/287031-memories-trophy-cg-library.html

So...
Page 1
CG 1-7: Asuna's events from Aincard
CG 8: Asuna's bed scene
CG 9: Asuna's ending from Aincard
CG 10-15: Lisbeth's events from Aincard
CG 16: Lisbeth's bed scene

Page 2
CG 17: Lisbeth's ending from Aincard
CG 18-23: Silica's events from Aincard
CG 24: Silica's bed scene
CG 25: Silica's ending from Aincard
CG 26-31: Leafa's events from Aincard
CG 32: Leafa's bed scene

Page 3
CG 33: Leafa's ending from Aincard
CG 34-39: Sinon's events from Aincard
CG 40: Sinon's bed scene
CG 41: Sinon's ending from Aincard
CG 42-44: Yui's events from Aincard
CG 45: Yui's ending from Aincard
CG 46: Strea's story event
CG 47: Strea's event from Aincard 100th floor without blue quest (you can miss it)
CG 48: Strea's events from Aincard

Page 4
CG 49-51: Strea's events from Aincard
CG 51: Is from event on 90th floor (you can miss it - maybe)
CG 52: Strea's bed scene
CG 53: Strea's story event
CG 54: Strea's event from blue quest on 100th floor (you can miss it)
CG 55: Strea's ending from Aincard
CG 56-57: Philias's events from Aincard
CG 58: Philias's bed scene
CG 59-60: Philias's story from Hollow
CG 61-62: Philias's ending from Aincard (you will get both at once)
CG 63: From defeting hidden boss after Aincard story on floor 100 (you can miss it)
CG 64: Hidden char #2 from Hollow (you can miss it)

Page 5
CG 65: Hidden char #2 from Hollow - after join quest (you can miss it)
CG 66: Hollow story
CG 67: 66/68 class S food event with or without Philia
CG 68: 66/68 class S food event only with Philia. You will get 67 too (you can miss it)
CG 69: Aincard ending
CG 70: Hollow Heroine Quest: Asuna
CG 71: Hollow Heroine Quest: Lisbeth
CG 72: Hollow Heroine Quest: Silica
CG 73: Hollow Heroine Quest: Leafa
CG 74: Hollow Heroine Quest: Sinon
CG 75: Hollow Heroine Quest: Strea
CG 76: Hollow Heroine Quest: Philia
CG 77: Hollow Heroine Quest: Hidden char #2
CG 78: Hollow Heroine Quest: Argo

First thing first - you can take as partner and date all you want but only these girls will give you something:

• Asuna
  
• Lisbeth
  
• Silica
  
• Leafa
  
• Sinon
  
• Philia
  
• Strea

Dating
You can increase affinity in two ways:

• Dating - in city or in garden (La Upultuea Gardens) you can talk with girl when yellow bubble text will appear. Then from time to time you can choose 1 or 2. Better answer will give you more points for affaction (you will see notes. More better.). If you increase first bar to max before second disappear you will increase mood level by 1. Increasing mod will give you more options for girl like: holding hands, picke up for bed scene. On max - 5lv, when you picking up has 100% chances. But still you can do it fast. You cannot be seen by anyone or you will fail and mood will drop to 1. How to pick up? Go to inn and before stairs talk to girl and use pick up. On max affinity level you don't need to increase mood to pick up a girl, so for bed scenes best way is praising. Only for memories you can use this for Argo and bonus char 2. Best places to date is fountain, bridge or dead end at schoop map. Btw you can interact with some places with V key (sitting next to table or other places)
  
  
• Praising - it's much slower way to do it but you will have plenty of time if you want do all in this game. Durring battles sometimes you will see in left down corner icon of: sword, shield or stars you can praise her ("Nice job" command from call palette). It will say to her to do this type action more and you will also receive 10% CD reduction and SP. you can praise her without icon but you will receive less notes. And you want praise her in right way... to got all hidden costumes.

How to praise and heroine hidden armors
Talk to girl in city and choose "Character information" -> "View Character information". On left you will see 3 diamonds:

• Atk - praise girl if you see sword icon
  
• Def - praise girl if you see shield icon
  
• Buff - praise girl if you see stars icon

All girls from list above has 4 armors: atk, def, buff, and ultimate for all 3 other and they are good. So all you need to do is fill one diamond above half. It doesn't matter if you will increase it in max for 2, or less but for 4. You must have in total more than half.
Every girl is better in some way, but you can talk to them to ask for more buffing, deffending... I didn't do it so you can ignore talking. Only remember that it will affect girl's AI, so fill last diamond type like you want her to play. If you want her to be offensive take attack, if defensive (she will provoke monsters so if she is weak will die offen) take def.
Then all diamonds has 4 ways to increase. 3 are special and 1 is common for all diamonds. You can wait for girl to ask your help then praise or use special command (check skills on call palette, they are on the left) to make girl do something which will help you to fill diamond you want.

Atk diamond

• Offensive support - she will help you attack. Or ask you for use aoe skill or normal skill
  
• Cooperation - for combinaction attack. it's simmilar to offensive support so i could do mistake. To see combination attack she will ask for use skill anyway so...
  
• Switch - "Swith" command - she will switch with you (target and hate swap)
  
• Sword skill - "use your skills" - she will use skill to attack (it's random. you have better chances to have icon from most filled diamond with it, so if she is more support type then after you will see stars icon from buff diamond, but not always)

Def diamond

• Hate - "draw them to you" command - she will provoke monster
  
• Cover - ???
  
• Def support - "deffensive support" command - she will use defensive skill
  
• Sword skill - "use your skills" - she will use skill to attack (it's random. you have better chances to have icon from most filled diamond with it, so if she is more support type then after you will see stars icon from buff diamond, but not always)

Buff diamond

• Recovery - for healing you
  
• Stunning - "Stop that move" command" - she will stun enemy. Also she can ask you for stun, then stun enemy
  
• Interference - buffing
  
• Sword skill - "use your skills" - she will use skill to attack (it's random. you have better chances to have icon from most filled diamond with it, so if she is more support type then after you will see stars icon from buff diamond, but not always)

There are two commands that i don't think will do anything for praising: "Witchdraw to rear" and "Replenish HP".

In short for atk i used swith at start of battle, use your skill command and all calls her to help her with sword. It's easiest diamond to fill beacouse most of her calls are for use skills. Sometimes stun:D
For def i used deffensive support and draw them to you commands. plus use your skills
And for buff stop that move command then she will cast buffs too . Plus use your skills

There is one important thing. If you increase one diamond, other will decrease so praise only when you see right icon.

To wear armor talk to her and go to Character information. if you have armor, you will see new command.

Bed scenes

• Each girl has 5 bed scenes, but for CG you need only 1. Other has the same CG but different dialog
  
• You need level 5 mood or level 5 affinity
  
• When you pick up hold walking key untill you will see dialog near bed in next room or you will drop girll. It's bug. And hold walking even durring loading screen

Quests

You can find 3 extra chars who can play with you. 2 are from Hollow and can be with you only there, third is for Aincard.

• #1 - First we can find in The Fallen Paradise in Hollow. If it's good place then you won't see minimap. To get her you must go there alone. Then straight ahead and talk with her. After each talk you must exit area and re-enter and talk again. This char is always here so if you don't see her then it means that you must push plot of Hollow ahead. My final talk was after Hollow last boss, but didn't check it every time
  
• #2 - Second is in Strait of the Offering. It's all like with firtst one. Be alone and talk until she agree, but then you must do side quest. Got to Research Vault and fight with 2 waves of enemies. First is easy, secon will one shoot your partner, so train her to about 110lv or... be high level with aoe attack and one shoot emeies. Saw it on Youtube but was to hard for me. After that she will be aaded to your friend list. You need her to complete all CGs.
  
• #3 - last one is easy, after final Boss of Aincard, choose yes to meet hidden boss. After win she can join you. I'm not sure if you can use her in the same playtime beacouse i found her after new game+ And this one can be use in Aincard too

It's end game dungeon which you can fight with enemies from low level to max level. And it's random generated dungeon, like this from last mission in Hollow story. You can enter it from main lobby in Hollow on right, but you need go futher in Hollow story to unlock.

There are 2 entries here:

• Undeground Floor 1-200
  First you will start from level 1, then you can enter every 20 saved levels until 181. You must know that there are no autosaves! And you can manualy save shortcut after every 20 levels, so: 1,21,41,61,81...181. Remember to use crystal to exit in next room after special room with boss or many enemies. Don't use crystal in the same room!!!
  In every level when you reach crystal you can go futher or exit. And if you die in, you will lose everything!
  Every 10th level you can find special room with lot of enemies (early) or bosses: starting from 1 or more NM, then bosses from hollow areas, and Garden's bosses at end.
  Every special room you can also use special crystal to make skill points or take random weapon with stats from level you are, so higher level of Undeground Floor then better weapon. This weapon can have unique skills like more exp, poison and more. I don't think it's better than you can find from other places but that unique skills can help in leveling or battles with human bosses.
  After 200th boss in chest you can find ultimate bow
  
  
• Classifield Zone - Abyss
  It's ultimate hidden boss which you can ulock when complete boss on Undeground Floor 200th floor. He can use all skills and has max level. But it isn't to hard if you will deal poke damage and run away in circles.
  You must have these skills: Clones, immortality, Perfect Aim and any attack with multi strikes. And he will use it also, so how it goes?
  
  Perfect Aim will destroy Immortality
  Clones will destroy Perfect Aim
  And multi strike skill will destroy Clones
  Perfect aim and immortality are time sklls, they will be in use until worn off, and clones are perfect immortality but only on about 10 attacks, this is why you use multi attack to worn off it.
  So all you need to do is use all 3 buffes, use multi attack until you will start to do damgae and use best combo, or skills until your immortality worn off, then go back and run away until you can use all 3 buffs again. And don't use ultimate skill from Garden, it needs to much time to activate and you will miss.
  I read also than you can use poison sword to stun lock him, but didn't try
  After beat him you can find second ultimate sword

So how to play here?

• Single
  Use it for fast skip floors. Buy invisibility drinks (10 is max) from schoop in Aincard, then don't fighy until boss floor. You must kill him to open door. Beacouse you will skip floors you will be much weaker than boss, so use Perfect Aim and Immortality buffs to fight. I had aboud 250 level when beat all bosses, plus hidden boss and had only problem with Queen boss, beacouse her minions.
  
  
• Multi
  Here you will have extra help from party of 3 girls, but monster will have higher levels... of course it's not big problem, you cannot have monsters with higher level than max, so you will hit max level monster ealier, that's it. Invisibility drinks don't work on your extra girls so they have no use here. Also you cannot use crystal with random weapons but instead you will autosave when you die! Yeah! So multi is best place to exp high levels. When you die you will keep your earned exp and drops and only you will have to start from last entry save. I tried to farm here but it was borring, so after week i changed on single and skipped all floors:D Plus you must kill everything untill boss, so if only boss is your problem then it's pain in ass to die on boss floor after 1-2hours on climbing.