I was quite confused when after over an hour of playing there hasnt been an achievement popping up.
Other games give you some after you reached this or that milestone. (Complete Chapter 1 etc.)

I initially thought maybe there is some issue....BUT NO!
After looking up the achievements available I gotta say:

THOSE FEEL LIKE REAL ACHIEVEMENTS

at least for now.

I didnt progress far enough to see if some of those are obligatory through leveldesign (e.g. the only way to proceed with the stage is to kill x-amount of enemies at once etc.)

I'd welcome achievements like these way more than just complete/find/unlock stuff. Not everyone might be able to complete the game this way, but the reward you get from this is way bigger imo.

What do you guys think?

/edit//

ok

I played a bit more and I got some more of those "just reach that point achievements"

I wonder how many I will have unlocked after I finish the game.

Probably not that many, since there's only like a half-dozen "hidden" achievements. The rest are either for killing enemies a certain way, or not dying, or finding all the collectibles (there's an upgrade that really helps with that)