In the how to play section, i didn't realize there were multiple pages of text. I think it would make more sense if next to the OK button there was another NEXT button. I see your game is on NG now! They can be a tough crowd for sure. It can take a while to build a following, and gradual improvements to your game are a big help. If you release any big updates be sure to post about it too because that will make people notice.
I would suggest maybe lowering the bar for some of those achievements. Players can be motivated by achievements but you have to give them some right away and pace them out so they have achievable goals. 1000 points would make more sense for first achievement. High score boards would also help bring in players, you probably could use 4, for each combo of sheep/chicken chill/stress.
I did not realize the timer was going faster with each hand but honestly I don't think that's a good idea. Players expect timers to go at the same time. There are many other ways to achieve the same thing without changing the the rate. Maybe just give less extra time for each hand and start off with less time initially. If you give less time, presumably as little as 0, and have an upper bound on time, you can put a much better time lime on the game. More options to increase difficulty would be add random junk tiles, add more colors of sheep.
Another small thing I noticed. I am not an expert player but it doesnt seem necessary to show the next piece for all 5 pieces. I'm sure it could help plan in theory but just feels like information overload. Or maybe since you already implemented that, only show it in the chicken mode since that is a more advanced mode?