Hard mode is a bit more difficult. I think I killed off my first village before I got it right. The second one I almost killed because I forgot to do the first puzzle. My strategy was to put on on building just until they were a trainee to finish that puzzle, of the others, I had 2 on farming and one on research, and then I put the builder on research. I kept the game running only when I was watching it, until I had a sufficient amount of food stored and had maxed out my farming tech. I also kept the kid on the lookout for mushies.

I've seen different advice about the food, but I generally prefer to food stores to be 400-500 before I put a third person on research and start worrying about techs.

Until you have enough food, don't worry so much about the other techs. They are pointless if your villagers die.

The hard game is a lot more difficult. Two days after I started a new hard game I started an easy game just for kicks. Within 48 hours the easy game had surpassed the more difficult one in techs and food stores.

Just keep trying until you get it right

I hope this helps, I didn't want any spoilers in case someone who hasn't played yet reads the posts.