I love this game! Heads up though that I barely use the weighing scale. I usually just chuck them into the incubator and see if they move. Nothing bad happens if I put an empty egg into the incubator, so I think the scale itself isn't that useful as it is. Still an amazing game though!
If I may give some unsolicited advice, maybe you could limit the amount of eggs in the incubator, then have a separate egg storage for the rest. That way people can't just put eggs in the incubator without thinking and they'll have to use the scale. Also for the eggs with chicks inside them, maybe they could start shaking only when they're almost about to hatch? Not too early :)