I was thinking about how new players can be retained and I got to the conclusion that a system with daily challenges might help with that.
You could have like 3 challenges each day, e.g.:
- Train drivers
- Buy a staff member
- Take part in a sprint race
These could keep players more busy with the game.
Of course for completing a challenge you should get some kind of reward, which could also compensate the fact, that there are no more daily rewards for watching ads in the store.
You could also add rewards for the already existing achievements you can get in the player’s profile.