Gathered feedback of a series of Let's Plays on youtube (https://www.youtube.com/playlist?list=PLxMKmR6sPm__O-tXH9e_dWIhQztZNJQ4v) using OC 6.1:

1) The raid: oil barrel must be dropped in front of the plane, this is unclear. Solution: write clearer in goal and use interaction menu to put oil barrel into plane.
2) The raid: oil barrel can collect water and spray water. Player thinks oil is gone. Solution: block this.
3) The raid: players take quite a lot of time to find the chamber with oil, maybe the hint could be more clear, or the landscape could point more directly to the secret chamber.
4) Ingame menu is too small, the one on [F].
5) Expectation to drop items in the wooden cabin, but this is impossible. Maybe the wooden cabin can function like a chest with infinite capacity?
6) Crash Landing: the player build one wind generator to power his settlement, and the wind was changing direction a lot and he barely had any power. Problem here is mainly the communication to the player, because he did build it in a suboptimal spot next to a tunnel, which means less power. Possible solution: change description of the wind generator to include these issues. (We could tune the engine also a bit that wind turns around less often and is also staying less in the central region around zero wind.)
7) Crash Landing: chest is missing.
8) Player could not find "Kohlekraftwerk", we could rename our steam engine to something more useful. Admitting, the player did not read the description of the steam engine.
9) Crash Landing: the player thinks the crate is for storing things and could only put 4 items. I'd suggest to remove this item from all current rounds.
10) Crash Landing: enable battery to allow for buffering power.
11) Crash Landing: Catapult NPC buggy.
12) Utter frustration to find the airplane and then to fly it away. It was facing the wrong direction. We need controls to turn around the airplane when grabbing it.

This is the feedback I gathered from the first 11 videos.