Hello. Here is the play/watch order:
1. play Danganronpa: Trigger Happy Havoc>(Danganronpa: The Animation is an adaptation of this game, and it's bad, so don't watch it)
2. play Danganronpa 2: Goodbye Despair
3. optionally play Danganronpa: Ultra Despair Girls>this is a spinoff game that you should only play if you really like the series and want to know more about the story
4. watch Danganronpa 3: The End of Hope's Peak High School, which has its own fucked up watch order>this anime is not an adaptation of any game, it's its own story; YOU CAN SKIP THIS if you want to, but there might be minimal spoilers in V3
5. play Danganronpa V3: Killing Harmony.