Ooh, that’s a good one! The MK8DX Booster Pass also.

I don't get peoples love for Erd Tree, that was a big empty convoluted mess with a disaster of a final boss. Only two good bosses in that and the rest of it was meh.

DOOM: The Dark Ages Revelations. It turned a game that was good but easily the weakest of the modern Doom trilogy into the 2nd best with gameplay so great it's not far behind Eternal in terms of quality.

Ruins of Kunark, Scars of Velious, The Shadows of Luclin, Lost Dungeons of Norrath, The Burning Crusade, Wrath of the Lich King.

Is that WoW?

Oh, I'm interested now. I'll stick The Dark Ages back on my wishlist. 

If you like a good challenge then a suggestion I have is to do a 2nd playthrough with the game speed turned up. I did a first run on Nightmare but the 2nd playthrough I did with the speed set to 150% and in general almost all the sliders set to their most difficult was a very enjoyable experience. It really forced me to be on point at all times.

Since Wing Commander is my absolute favorite series, I have to mention all the expansions: Secret Missions 1&2 (WC1), Special Operations 1&2 (WC2), Righteous Fire (WC:Privateer) and Secret Ops (independent expansion of WC:Prophecy). All of these are great in their specific ways. WC1 is the best game itself, so objectively "just good" Secret Missions expansions are more of the great. Special Operations 1&2 have best story of all the games and some more fun parts. Righteous Fire and Secret Ops are actually best expansions: basically you get a second similar game, with slight improvements to design.

Aside that I want to say Icewind Dale 1: Heart of Winter and it's free add-on Trials of the Luremaster (both included in the later IWD: Enhaced Edition).
And while we're at that: Baldur's Gate 2: Throne of Bhaal.

Imagine calling Dark Arisen 2 “side content” ……..

Some of the best expansions I’ve ever played are Dark Arisen (1), Dragon Age: Awakening, both significantly better than the base game. CP77: Phantom Liberty is one of my all time favourite expansions to one of my favourite games. I actually really liked Fallout NV: Dead Money.

My biggest complaints after 2016 is Eternal felt too fast and too intense while also trying to be precise with body part targetting but DA looks too slow from what I seen of it and still tries to be precise with parrying. If there is a bridge between the two I'd be all for it. 2016 was just right in this manner.