According to the documentation in https://www.forgottenempires.net/age-of-empires-ii-definitive-edition/rms-features in DE exists similar to UP 1.5 the command direct_placement, which together with create_land and the command assign_to_player N can be used to create fixed position maps. The problem with this is just, that assign_to_player N only works over the player slots (the order the players joined the gameroom) and NOT the player color as it’s the case in UP 1.5. That’s a huge problem because this makes the whole command unuseable in practice, players have to join in the exact right order else everything is messed up, which is very difficult. If the command was done as in UP 1.5, all players can join in whatever order and simply pick their color according to their preferred spawn location.
You might now ask why am I not using the build in fixed position setting, well because first this command offers very little freedom for the spawn locations (spawn locations are always randomly done, while with direct placement i can exactly force specific locations for specific players), second everyone always knows before the game where everyone is, vs which enemy he is up to and vs which civs, which is quite problematic since everyone tries to counterpick/avoid certain enemies etc. This can lead to disputes and huge delays. However if the spawns are done with direct placements, it’s possible to bypass this issue with writing a rms code that randomises the flanks/pkts. Maps using this have already been used sucessfully in tournaments on voobly.
TLDR: please, please change the command assign_player N in order to let it work over the player color and not the playerslot in the gameroom, to make customized fixedposition maps as in UP 1.5 possible. This is very, very important for larger TG tournaments, that in future will be using fixed_position maps.