Hey, PGad! In the first level you need to talk with the man in front of the house. This triggers a mini game. After that you need to speak with that person again. Then you open the inventory and click on the mobile phone. Finally you speak with the deminer to proceed to the second level.
The first part is like a cutscene which needs your input to move along. It's linear because it shows parts of the system. You will see that all the other meetings are free flowing.