@Atrik Apologies for only responding now. Considering that you have now set up a Gitea account and fork in the meantime, do you want to open a PR for this now? I'm still up to do the testing and reviewing. (If not, it's also fine, I can take care of all the git stuff for you, if you want)

I just build some minutes ago state d3406f4509 with git clone -b release-0.28.0 https://gitea.wildfiregames.com/0ad/0ad.git Under https://gitea.wildfiregames.com/0ad/0ad/wiki/BuildInstructions sudo pacman -S --needed awk openal m4 boost cmake curl enet fmt gcc gloox grep icu libgl libogg \     libpng libsodium libvorbis libxml2 llvm make miniupnpc patch pkg-config python \     rust sdl2 subversion wxwidgets-gtk3 zip zlib should be cbindgen added. I can play with the established civs but when I try to play a single player game with the germans I get these errors: ERROR: RelaxNGValidator: Validation error: special/players/germ:1: Invalid attribute comment for element GenericName ERROR: RelaxNGValidator: Validation failed for '(null)' ERROR: Failed to validate entity template 'special/players/germ' ERROR: JavaScript error: simulation/components/PlayerManager.js line 20 Engine.QueryInterface(...) is null PlayerManager.prototype.AddPlayer@simulation/components/PlayerManager.js:20:9 LoadPlayerSettings@simulation/helpers/Player.js:44:21 Setting biome generic/sahara. Creating playerbases... 0.014223s. Creating bumps... 0.099461s. Creating hills... 0.019315s. Creating forests... 0.033423s. Creating dirt patches... 0.023661s. Creating grass patches... 0.010003s. Creating metal mines... 0.003676s. Creating stone mines... 0.002799s. Creating decoration... 0.009231s. Creating food... 0.001154s. Creating food... 0.000527s. Creating straggler trees... 0.015792s. Total map generation time: 0.239990s. Total entities: 1832, Terrain entities: 665, Textures: 13. WARNING: GetPlayerByID: no player defined for id '1' PlayerManager.prototype.GetPlayerByID@simulation/components/PlayerManager.js:91:16 ERROR: Failed to load entity template 'structures/germ/civil_centre' ERROR: Failed to load entity template 'units/germ/cavalry_javelineer_b' ERROR: CColor has to be an object ERROR: Error calling component script function GetDisplayedColor

Cool, thanks for the help, I’ll let you know if it works.

I think you might have to do something like this : Add a "submarine" section in there pathfinder.xml with a nonrestrictive "shore distance". Handle it in BuildRestrictions (maybe also some stuff here Templates.js). Then you should be able to add <PlacementType>submarine</PlacementType> in <BuildRestrictions> in templates. Don't forget to fix petra too!

Is it possible to build underwater? What would I have to do to add a new building placement class, that is like the standard one but can be built underwater?