Thank you very much! Yes, I overscoped quite a bit. Originally four areas were planned of which only two are in a fairly playable state (not counting the starting area).
The interaction with the context using the E key is a bit lacking indeed, even buggy at certain points.
The idea at the start is that you go inside the train cart, then push it forward until it starts moving on its own. It doesn't matter if you're connected to the cart using E or not.
Ah yes, the Demoscene :). Definitely looking forward to that!