I want to recreate the world [old game] HELP

I want to create something new in an old game, create new areas .
Old Game is 4Story
But unfortunately, I ran into bigger problems in the beginning .
In an old post on another forum, I found that files were opened with Unity
But I failed to load them with it .File format is .tmu

I will upload here a picture of what I found in another forum
And I’ll even upload a file of the maps and other files from the game