D:, just wrote half of the answer, switched tabs on phone and it got deleted, hate u forum
On models like those, you start with a blueprint, a drawing of some important details to guide you trough your modeling. Also, you add some guidelines on the program you are using.
Once that’s done, you start with briefly creating the shape of your object. I’d separate that one into floor, walls, door, roof, windows and the tower. It’s important to keep your model low poly at this stage, so don’t get too exited yet with fine details (I mean, you try to get the highest quality possible with the nodes you have, but you shouldn’t add a lot of vertices yet)
At this stage, your object won’t have any color nor texture. Once you have the basic shape of an object, you should create it’s UV map, which will tell your program how textures should be added. Then you add and configure your textures, and start painting them over your model (painting isn’t always needed).
Once you have that done, everything will be starting to look more like the idea you had when you started your model, but you are not ready yet.
Now you get to the fine details, to do so, you save your low poly version, then you subdivide your mesh, and use stencil tools to make some really fine and awesome details (marks on the walls, drawings on the door, some imperfections in the roof, etc).
If that’s done, your house will be looking awesome, but it will be too heavy to use it on your game. Now you add you bring your low poly back to scene, but first save the high poly one. You should put both models in the same place, so they kinda ‘merge’, and use your program to generate a normal map. Once you have the map, you remove your high poly from your scene, and add the normal map to your low poly house…
It’s magic (well, tbh, it’s science), your low poly will now look like it’s high poly version, but won’t be that heavy, so your house now it’s ready to be included in your game.
Obviously, this is just the briefly explanation of the process. Every step have really different techniques and tips which you will be learning over time. My recommendation would be to start with blender, and not to discourage yourself if you don’t like the results at first. As everything releated to making games (and what’s more, most things in life), it takes lots of practice and experience to start getting nice results. Wish you luck at modeling.
One more thing, if you are kinda crazy and would like to go even further than that, shaders will also help you on making everything look even better (be warned, that one is a really hard topic)