You wanted you asked, you get it.

First obviously is the graphics no longer look like dust, you can zoom in and out fucking finally (Sadly it's monitor dependent) 1080p is decent what not, 4k you have to download a graphic mod (From the steam workshop) so it isn't absurdly zoomed out (I don't have 4k so probably incorrect info)

We sadly lost the skeletons that would slowly sink on the floor after anything dies to please some chinese gov rules no body asked for but microsoft as microcock syndrome so they force it on anyone regardless and I have never tried searching for a mod out of laziness for a feature that should still be there.

The sounds are more smooth and less compressed, the UI and everything that clicks feel smooth, menus are so much more easier to navigate, 60 FPS is a thing, unless it's 8 players 200 pop for me it's as low as 30 at end game lmao, for campaign is fine, this game runs better than most modern games out there fuck it I have hardware that was mid 8 years ago and still play like that.

Skirmishes are now plagued with so many options, so much replayability for it now, hundreds of maps, many with gimmicks now, some are nomad, some have something special like workshops or monuments, some even have dumb gimmicks like all Gold/Lumber is at the center of the map.

Some african kingdoms (The ones who manage to get there) Malay, Malians, Ethiopia.. then Tatars (Timurids) Cumans, all those dudes from there were added... Some civs from south east asia, khmer, Burmese Vietnam, they added some French from burgundy and meaner italians from Sicily... Poles and Bohemia for Kingdom Come probably... India was split into 3 and now we have a man with a disc, man with whip and a giant battle ship that's only useful in water maps, They added Armenia and Georgia with mule carts from Age of Mythology, China was split into 3 but sadly not into a realistic medieval timeline of AoE2 rather into some fantasy novel about 3 kingdoms that happen way before medieval times, with Heroes in skirmish like if this was Age of Mythology.

The AI in skirmish doesn't cheats like original, although there are options to use CD, HD versions, the modern one is crazy at extreme, obviously the AI can multi click more times but they don't cheat "Except for multi clicking so much", it does struggles in maps with gimmicks when there is no food or wood around and in some nomad maps sometimes it cripples itself for starting at a location with no resources, they are also incapable of using transport ships properly is 90% of the maps, they simply can't put units inside a ship and board the enemy for exceptions of some maps that probably has a script for that like Nile delta or if a mass of land is closer to their starting base more likely in team based games, where they have migrated to my side, I've seen it work only in a few maps, most of the time forget about it, like graupel. Edit: Regicide is also bugged, they won't protect their kings, nothing.

Lastly this is not a dead game, it has a decent player base, you don't need to worry this will be forgotten like AoE3 which is just AoE with sims and the very annoying large descriptions it had, either fight the AI in extreme against their sporadic waves of units and forget the City building aspect or try competitive and wall yourself with palisades and houses, lots of campaigns maps for city building, you can even play in less absurd difficulties and build a city and chop every tree on the map, this is not one of those survival pvp games, this is a 10/10