Hey guys! How do I change the type from single scenario to multiplayer arena?

Open the map with any archiver, for example, WinRAR. Go to the Maps folder and rename the SingleMissions folder to Multiplayer.

Added 15 minutes later

Hello,
I need to set the game stages to last for several weeks (tens, hundreds, thousands 😅), and people are having trouble with retraining to keep things fair. For now, I've implemented a workaround using monsters as NPCs and a retraining function with some recalculations. But the question is, can I redefine the value of a variable during the game that controls the retraining of creatures per week? And so that it is displayed directly in the city interface, indicating that you can retrain, for example, not 7-20, but 100-500 creatures. If possible, what is it called, where can I find it, please advise.

If you need everything to work as you described, then it is very difficult. Variables stored in data.pak are compiled each time the game starts and can only be changed by third-party tracker programs like Cheat Engine or ArtMoney. If you need a relatively simple solution, I advise you to create several versions of the map for different stages of the game, where the parameters TrainingPointsPerWeek and TrainingPointsPerWeek_Upgraded (which are standardly 7 and 20, respectively) will differ. These are located in GameMechanics/RPGStats/DefaultStats.xdb