OG coming back to AoM after 10 years, any tips on what to expect and what not to expect? Also insights on MP.

Big time AoE fan, played a lot of AoM 10 years ago, but then came AoE3 and AoE2HD and I somehow stopped playing this game (lack of multiplayer also contributed to that decision)

Now I am about to buy AoM EE on steam to return back to my favourite RTS.

But times have changed, please give your insights about major changes that have happened in this game. (I know new Civ added, but besides that are there any changes in game engine itself?)

And please tell me about the MP scenario, are there enough players on steam?

Also I believe Relic games now holds the rights to AoM based on what their website suggests. They are working on AoE4, do they provide patches or updates to this game?