Thank you for the feedback! I am aware of the bug where you return to the main menu after playing and re-entering doesn't work. This seemed to be a bug in the Unity3D Linux version, as even after trying a new project I experienced the same issue.
Sorry for the bland world! I wanted to fill it with more greenery and interactables, but I ran into issues with baking the Lightmaps and baking the Nav Mesh which cost me too much time.
I should have put more information in the instructions, I definitely missed out putting how the player moves. WASD is correct and E is indeed the pickup key. Seriously, thank you for taking the time to try it and reporting your experience back to me, I appreciate it :)