Symmetric / Mirror maps

[elexis]

The succeess of Mainland: Despite a variety of maps being available, a huge portion of lobby players prefers the Mainland map.

The intent is not to be surprised, not to have to discover things, not to vary with regards to the map, but to solely focus on a petri-dish economy growth, focus on the enemy interaction and discovering new strategies, build orders and tactics that work independently of the map.

Notice mainland consists of only 12 map generation statements, one of the top 5 files of fewest lines of code.

Mainland fans mentioned they would prefer a new map only if it would be a mirror map. They want everything that mainland has, plus even less surprise (resource balance) in the map generation.

So for these players 0 A.D. could provide one of the following:

• A new random map that always generates perfectly symmetric maps. _kali had uploaded one, but the code was incomplete: #4760.

• A gamesetup mirror-map gamesetup option for random maps. The more of the 65+ random maps implement it, the more of these maps might be played by these Mainland fans. Since some random maps work with fixed terrainmaps, it will be nearly impossible to implement this on some maps. So it likely requires #4838.

• A gamesetup resource-balance or resource-distribution gamesetup option. This might or might not be as impractical on a number of maps.

[FeXoR]

We don't have any perfectly symmetric maps IFAIK so, yea, lets fill the gap.

A map filter for that would be nice.

An "symmetric" setting optional for maps might be good (I definitely think custom map settings is a great idea) but I#m not sure if most maps should have that.

The "balance resources" option is IMO not needed. Maps either aim to be fair and then they usually are quite fair or the maps accept more randomness for the sake of variety in which case they are hard to make fair (by means other than symmetry, which is the previous point).

Besides not solely mirror symmetry is meant but also manifold mirror symmetry, rotation symmetry and (central) point symmetry (and mirror symmetry with translation symmetry).

I suspect there are further preferences of the majority of (competitive online) players, so what about:

• Random biome or rather unique but fixed set of textures/entities/actors
• Cliffs (like Ambush) or Bumps (like on Mainland)
• Chokepoints (If so, how broad? 7-11 tiles wide?)
• Only tight groves (opposed to single trees or low density areas of trees)
• Nearly round Puddles of water (opposed to longer lakes, Rivers [with bridges/fords or entirely walkable or only conquerable by boat], fjords and bays)
• Map border: Water, cliffs/hills or plain

After those points are determined I guess there'l be a rather precise design description of a map that suits the competitive gaming community ;)

While I'm all for this we shouldn't loose single players out of the bigger picture.

[badosu]

For reference, I noticed the lack of fair maps for competitive 1v1 games and started addressing this issue on balanced-maps mod:

• ​https://github.com/badosu/badmod/
• ​https://0ad.mod.io/balanced-maps

The approach is quite simple: it's not necessary for the map to be completely symmetrical or not have imbalances mid map, we generate equal resource amounts in reasonably random positions for early to mid game.

We also do it per map, as for the current scope it would be far too ambitious to change the random generator helpers in an effective way. It also ensures the mod is compatible with vanilla.