Oh, and just to make sure you don't miss anything, small walkthrough:

1. Hear the first conversation.

2. Talk to everyone and exhaust all dialogue.

3. Walk back to Mars.

4. Talk to everyone again.

Each edge of the world has a prompt too, right at the center area.

v0.1 adds a small bug fix to the prompt system. You can use that one if you have trouble with the original (content is the same in both version though, you can verify that if you care to play both). Also, I forgot to mention two other controls: the Space bar makes the character jump, and holding the left shift makes it run (sort of obvious, but I though better to mention it anyway).

Controls:

WASD or arrow keys move the player.

Left click changes dialogue. Also used to interact with prompts when they open.