Totally agree for some tools like "tree brush" Inspired by my little experience on Atlas, and some child memory of Stronghold and Empire Earth 1 not by "importance" just by head 1 A way to set Diplomacy between team/ player ? (I dont find any without code ? ): Player 1 is enemy with Player 2; both is Neutral with Player 3 2 Somehow, the water level should be higher by default, or the "ground level" should be lower, In default setup, it seem I have to dig way too much to see water (compared with unit size) 3 An "auto-passibility-tiling" (dont know how to name that) but when modifying the terrain, if it become impassable, "colorise it" with a cliff/rock texture automatically 4 Could be nice having some "preset" of elevation like flat (default ground elevation), cliff (impassable) and "naval" (impassable/ underwater) and/or a "pipette" for elevation These 3 could make more easier the first draft of a map, making the big shape first then affine  5 Having a panel for "flora/gaia" entities (tree/rock/animals) and on for "players" entities(unit, building)  Always having the ability to set each affected to Gaia or Players but stored separately 6 The "simulations" buttons (play / pause/ reset etc) should be on the top menu, on top of the "world view", having to switch panel and scroll down to click, bother me xD 7 I would say the ability to edit "metadata" for unit / building (like current HP for wounded unit), maybe there currently a way, I just doesn't find it I'm really not a map maker, but Atlas doesn't encourage me neither :p 

My Windows menu entry's called 'Map editor'!

Also   

@ManasManushya  If it helps! I think simple tools (mods) that don't break anything when removed are the way to go. Post-Atlas helps me a lot with stats.  

@lilypoppyi think i shall also spend some time examining the 0ad's scenario editor (Yeah, its called scenario editor not atlas) so that i can see some by myself.