While I agree with your assessment of the bias of the Codex @lackblogger;, I must say it suits my own tastes quite perfectly. Not because feelings of tenderness towards Chris Avellone, but definitely because of feelings of tenderness towards games released in the time period you mentioned. And no, I'm old enough to have played games before that period.
Out of curiosity, could you mention a few titles you personally think should have made the lists top 20 rather than the ones who did?
Sure:
Any of Vogel's Exile series, either as Exile or as Avernum.
Blackguards
Lord of Xulima (much higher)
The two King's Bounty reboots from Russian devs
Drakensang: RoT much higher
Serpent in the Staglands
Neverwinter Nights (much higher - this time they didn't seperate any of the NWNs from their expansions or modules, so anyone reading it will assume they mean the Origina Campaign for both, which is appallingly bad communication)
Is just a very small taster of the kind of omissions and demotions from someone with my perspective, and this is before you take into consideration all the people who like all of the 'popamole' games that the codex pretends to hate, from Dungeon Siege through Mass Effect to Horizon Zero Dawn. But if you're development studio is based east of western Europe then your popamole is the best thing since sliced bread, of course
And then, of course, there's all the people who love their jRPGs, to which their list pays only the lightest cursory gesture while effectively providing zero evidence of any knowledge or interest in the genre.
And in terms of independent studios generally, the blind eye there is as blind as anyone else's, unless your 'independent gem' is some kind of fallout-clone. Fantasy independent goodness? Non-esistent or forgotten down the list somewhere, from Legends of Grimrock to Eschalon type stuff.
Likewise all the oldies are just a ramshackle non-sensical selection of nods, mostly the stuff that people like Avellone of Sawyer say inspired them or the flavour of the week favorite Ultima or Wizardry or MM game, with most other stuff consigned to the dustbin.