I have two ideas:
1.
When it is night time in real life, it can be night time in the game too. That the light in game is dark when it is night time in real life. And that we can buy lamps with coins to light up our farm at night time. And maybe also that the light changes throughout the day. During the night it’s dark and in the morning it gets brighter.
2.
Saving account.
Can you ad a saving account? So that we can transfer coins into the saving account and save coins for buildings and other things? It is often so easy to use way too much coins and it is hard to actually save coins.