I'm leaving this topic open for the discussion for people interested in attempting at a .hack game, to show off their progress on either a standalone or game/server client based on The World. If you have a game in the works, let us know your progress. If you need help, seek peer-to-peer support here, or if you need a team, pitch your idea here to find your team.
Useful links to programs
Text Adventure:
ADRIFT http://www.adrift.co/
Inform7 http://inform7.com/
Quest http://textadventures.co.uk/quest
Twine https://twinery.org/
Visual Novels:
Visual Novel Maker https://store.steampowered.com/app/495480
Ren'py https://www.renpy.org/
2D Game:
RPG Maker 2000 https://store.steampowered.com/app/383730
RPG Maker 2003 https://store.steampowered.com/app/362870
RPG Maker XP https://store.steampowered.com/app/235900
RPG Maker VX Ace https://store.steampowered.com/app/220700
RPG Maker MV https://store.steampowered.com/app/363890
Game Maker Studio https://www.yoyogames.com/get
2D Game & Server:
BYOND http://www.byond.com/download/
Eclipse Origins https://www.indiedb.com/engines/eclipse ... /downloads
Elysium Diamond https://github.com/legacygamedev/elysiumdiamond32
Genus https://github.com/jikoriko/Genus
Konfuze http://konfuze.atspace.com/HOME.htm
Mirage https://github.com/link2x/gMirage
3D Game:
Blender http://www.blender.org/
Godot https://godotengine.org/
Unreal Engine https://www.unrealengine.com/en-US/download
Unity https://store.unity.com/download
3D Game & Server:
MMORPG Tycoon 2 https://store.steampowered.com/app/4868 ... _Tycoon_2/
And should you have concerns about CyberConnect2 coming after your project, hear this statement from the CEO himself regarding fan projects.
Basically, go for it!, but don't tell us.
And BandaiNamco's statement.
https://www.bandainamcoent.com/legal/co ... guidelines
Basically non-profits are good, better if you don't copy/paste textures, models, or art directly from them.
Go forth and good luck!