Will I have to have watched the tv series to make sense of this game? Or Will I be fine to just jump in without any knowledge?
Here is a summery I made for Hallow Fragment during a sale thread in the past. It will give you the basic run-down on the story of Hallow Fragment.
"-SAO is a great action JRPG that has hundreds of hours worth of content with some of the Vita's most colorful visuals. The combat system is quite deep and the level systems will lead you investing hours into your characters. Great game that suffers from a bad translation (that can be funny at times) and expectation that you saw the anime prior to playing (up to episode 13-14). Made a catch-up post in the sale thread that I will leave here:
Regarding the story, look at the following:
-Takes place in a VR MMO, but the characters cannot log out due to that feature being locked out by the creator.
-Leads to everyone going into a panic, but coming to the realization that they need to beat the game to be free (which is 100 Floors of dungeons).
-Main character Kirtio was a beta tester for the game before its launch, so he is skilled with its systems
-He meets his harl....I mean, cast of female friends across the anime
-Gets close to a female player named Asuna and they become 'married' in-game.
-Their 'daughter' is a AI program that they encountered in one of the anime's episodes, who they took in as their 'real' kid
-Final battle in the anime was in Floor 75 and in the anime, after the fight with the creator of the game, it ended, with everyone going free
-This game (Hallow Fragment) takes place in an different reality, where the game DOESN'T end, it just goes on and glitches out
-The cast of the anime have to deal with this and continue through the floors until they beat the final boss on Floor 100
-Character introductions are very clouded, so I will explain them here: Sinon was bought to the world due to a glitch during VR therapy. Leafa (Sugu) was brought to the game on her own will; used a friends NerveGear (the things they use to play SAO) and loged in to see her brother/cousin. Strea is a 'new' player in the game world but is a AI program similar to Kirtio's daughter; originally a mental-health montaring program in the game but was brought out with the other players after the 'glitch'. Philla is a player affected by the 'glitch', who after 'killing' another player, is locked in the Hallow Area (the first playable area in the game you see) and you work with her to fine a way out for her
-Everyone knows Kirto is married to Asuna but they don't care because they all want him :l. Hey, the game creators couldn't fix everything from the anime XD.