Age of Empires II: Definitive Edition

This should be somewhat self explanatory. However some tips to make this easier:

1) Go for the map Coastal. --> Exploring the sea is quite easy with Elite Cannon Galleons
2) Turn on grid in the Options menu and zoom out to the max, this will help see the shadows better
3) Shared exploration or Spy will NOT work
4) It is an individual statistic found in the Post-game under the tab Technology
5) This achievement will pop Post-game
6) Don't send a ton of units everywhere. Take 2-4 on land and 2-4 on sea. Use the hotkeys to assign numbers to keep track
7) Uncover the map the same way you would mow lawns. That way you won't get a scattered map and you'll get a more cleaner approach to this, think gradual, not yolo
8) This will take about 45 min to do, you can try and get other achievements while doing this but it's not recommended

9) Building Outposts can help uncover those edges your Scout can't reach

Here are some tips:

Choose the Huns as starting civ with 500 population, choose post imperial. The Huns don't have houses so you automatically start with the max available population, mening you wont need to build tedious houses.

Choose Treaty Length 90 Mins - This means you can explore freely with out your explorers being killed. It should take around 50mins to fully explore but set to 90 mins.

As soon as the map loads, Set your starting scout to Auto Scout

Build 2-3 stables - Then send out the first ten horse units in multiple directions.

Your best friend will be Manual Way Points to use this feature select your unit, hold down SHIFT then right click, choose multiple locations and you will see waypoint flags appear, this is a massive help it allows you set units to follow huge routes without having to continualy click.

As soon as you see water build docks - Build galleons as they have bigger field of vision, theyre may be oasis of water inland so build a dock here. Make sure you follow the edge of the map around as its easy to miss bits

Other thn docks and stables dont build anything else, unless you are going for specific achievements

Finally, the achievement only pops when you finish the game and get to the stats screen, so dont wander around aimlessly waiting for it to pop. So make sure you save before you quit, if the achievement doesn't pop then you have missed a bit.

I played Marshes on death match on Post imperial age. Pretty useful play with Turks and explore by land (scouts) and water with Elite cannon galleons.
Don't have allies to not have shared exploration.

An alternative to the already existing guides if you want to idle the achievement.

Civ: Mongols (+2 Scout LOS)
1 AI in the same team as you so you don't get attacked.
Starting Age: Feudal (anything higher will share exploration with your ally, we don't want that).
Game speed: Fast
Resources: Infinite
Advanced settings: Turbo mode
Map: Arabia (a map where your scout can pretty much go everywhere on its own).

When the game starts, make your scout auto-scout.
Build a stable and a blacksmith to go up to castle age.
In castle age, research Husbandry so your scout moves faster.
DO NOT research Light Cav, it makes the scout slower.

Go do something else and come back later (I went to bed and came back in the morning).
The map should be explored and the scout not moving.
Save just in case.
Resign and the achievement should pop.