I'v been looking to a solution to this and it seems to me so far that factorio engine does not allow missions in sequences to end in a victory and unlocking next mission. with that only the last mission can have a victory screen and continuing the same map.
the best I can think of is two branches, with one allow the players to win and continue to next mission. while the other let the player continue current game, which mean the players have to repeat the ending twice and manually save, which is a clunky solution.
the best solution right now is what you suggested, with having all missions unlocked as sand box mode.
Work around A: require editing save
1- save the mission as a new save
2- navigate to the save folder, and extract the compressed mission
3- edit control.lua to have only the following:
require('__base__/script/freeplay/control.lua')
4- re-compress the save file and start the game
5- open the game console and type the command:
/c game.player.force.enable_all_technologies() game.player.force.reset_technology_effects()
I have an issue if the objective window is shown, I have no idea how to remove it and it stuck there.
Work around 2: in game only
1) save the level as a new save file
2) from the main menu go to Map editor -> New scenario
3) pick Freeplay
4) go to Surfaces tab and click the [Import save] button
5) Import the save file, and Import it As Nauvis
6) save the scenario
optional:
- go to forces tab, and click some where in the map to set player spawn point
this will start fresh, so you may want to re-unlock the research you already progressed in the editor.
