Oh, one of those
It was weird how a game featuring tanks was going to be a puzzle one. I'm no good at these kinds of riddles. The first one reminds me of that old one about the people at the bridge and one of them leads to the right path. I think the answer to this riddle is actually that both of the people are liars and you shouldn't go either way. I doubt it works like this, so congrats on you for making it hard. It's great to see such fine detail put into the game.
The moon itself isn't really blue, it's just the sky around it. Well, that's probably where you get the common phrase from. For those of you who are good at solving things, this is the game for you as it's going to take some time to figure out. Thank you for the walkthrough, which is always good. The music is also decent because it gives off a fine sense of wonder.