Single-family house on a slope with a basement for 2 people including home office and hobby rooms

It doesn't matter at all how many square meters other families roam around on. Even if they had an average of 10 children and lived on 80 sqm on average, what does that have to do with my house? Sorry, but that strikes me as strange. Even if I were to build 17 rooms on 1000 sqm...

Yes, it doesn't matter who has or builds what. Wasn't my statement clear? I don't see a plan there, but rather a hodgepodge of enumerations. It is unrealistic.

Wishing to sketch

And by that he meant you should draw? Or does he mean you should think about it and write it down? If the former is meant, I would change the gentleman!!! Or realistically commission and pay according to HOAI

If you prefer,

What I like does not matter. It should be feasible.

But that's exactly what I'm asking for. Explanations of what exactly doesn't fit and why and how it is unrealistic?

No idea what he meant exactly by that. Whether to draw or not. Of course, we pay him normally. It's just very difficult to express what I want in words. But in general, I don't really want to be fed something, but rather to work out something optimal myself.

Generally, I actually don't want to just have something imposed on me, but rather work out something optimal myself.

That is correct, because your cooperation is crucial to success. It consists of giving the architect a picture of your life, wishes, aversions, goals, habits, preferences, needs, etc., and then giving him the freedom for architecture that fits exactly that. That is division of labor. Bouldering, for example, does not get just any room; it is considered in the concept and implemented. That is another dimension and nothing for us laypeople. With a good solution, you immediately move away from the generic and still stay within budget.

Where is the basement plan? Topic statics: I assume you will also need load-bearing walls, you have only planned 12cm walls. Unfortunately, you won’t make it with 500k for the project. On a slope, you will probably also need concrete walls. Shell construction with a living basement about 350k-400k, construction site costs 10-15k, air-water heat pump in the range of 30-40k, sanitary 30-40k, electrical (KNX?) from 25k and upwards with no limit, a double garage will also cost you 50k. Then you still don’t have a paved driveway or yard and no exterior/garden landscaping.
Added to that are the "little things" screed, floor coverings, doors, painting/wallpapering, garage doors, kitchen and furniture, another 70-100k.
So then...

We are currently building a hillside house with 170 m2 + a basement in Brandenburg and I can absolutely confirm the price forecast from .