This is why it is necessary to combine maps into a campaign. Somewhere, you need to enter the names of the heroes, whose skills and experience will "carry over" from mission to mission. But you should ask Ser9K about the details – he is our master of campaigns :). P.S.: The maximum level in the game is 40. But it is practically impossible to reach – it's more than a billion experience points. P.P.S.: Creating a campaign requires phenomenal perseverance – because to create a standard campaign of five maps, you need to do the same, complex work on each of them – design the layout, write scripts, create videos. I tried to create a campaign, but the work stalled on the second mission. So, I advise you to start with single maps – feel out your capabilities ;).