I didn't understand at first that the food tiles refilled the entire meter, so I was picking them up as soon as I saw them and then losing because I didn't see another one spawn in the next few tiles. But once I had that figured it, I had no issues!
I think you could easily expand this to include more tiles types and resources as well as add some sort of goal the player is ultimately working towards. I'd also like to see a right click or middle click mouse panning aside from just edge-of-screen scroll.
Simple, easy to understand exploration game!