>>28763992nd game is a really good prequel
Season 1 of the anime is just a super rushed danganronpa 1, 2nd season is a whole new story involving the survivors, and 3rd season (which aired the same time as the second) was a prequel to Super Danganronpa 2 (the game).
It was a shitfest, but it was pretty fun to watch with /a/.
There's also the spinoff involving Makoto's sister and Toko, which is being ported to PC in a few months.