Indie game storeFree gamesFun gamesHorror games
Game developmentAssetsComics
SalesBundles
Jobs

Yeah.  Assetforge pieces models together and let's you export them as a scene or complex object.  I think you can use meshmixer and blender to make the exports more efficient for use.  Assetforge is here: https://kenney.itch.io/assetforge.  It's about 30 USD at the base price.

I see. Well, don't have the money, I'll handle myself on Unity xD, thanks again.

No problem.  If someone makes a good tool in Unity to put together modular kits like this and supports multiple tiers, let me know!

heads up, learn a basic workflow to import content into blender, assemble and export to unity. It's free and it'll take you a day or so to learn, but it'll literally save you hours each time you need to work with new content.

All the scenes you see were assembled in Assetforge in a few hours.  I put together 4 separate environments.

How can you create such a game

if that's a real question, the answer is that you will need to duckduckgo some tutorials.  Unity has a large community.  Also, there are premade game engines that do most of the work for you like uMMORPG