The Full Game Bundle (30 games, in 1 bundle) which includes every game in the series is available on PC and Android.

Check it out using the link below:

https://itch.io/s/91488/the-full-series-bundle-30-games-in-1-bundle-for-pcandroi...

Here is the correct play order :

1-Happiness 1 Definitive Edition

2-Happiness 2 Remastered

3-A Happiness Story

4- The Helpers Club [New addition]

5-Existence (RPG)

6-Milker (RPG)

7-Goodbye Time Traveler

8-Twilight Observer (Null 1)

9-Devotion

10-Waiting for Godot [Animated Edition]

11-Time Letter

12-Zero One

13-Reeva

14-End Of Happiness

15-Divinity

16-Carmine

17-Farewell My Happiness

18-Identity

19-Goodnight Mirall

20- Naz

21- Death Loop (Null 2)

22-SYSTEM  

23- Farewell My Despair

24-Hassan : A Happiness After Story   

25-Observer 1 + Observer 2

26-Butterfly

27- Intruder 

28- Null X

29-Extruder

30- CC Dating Sim: Forever With You