Your favorite game on your phone?

Since I'm always looking for recommendations for mobile games to play on my phone... what are some of your favorite ones? Mine are:

1. Tsuki, a relaxing game where you play a rabbit who leaves the city to move to the countryside...
2. Girl Alone, a sort of hikikomori girl that you interact with trying to make her feel better.
3. And I love Mahjong too, but that's a classic.

Which are yours? Suggest me something!