It's Ren'Py.
If you go to this wiki site, you will find a list of visual novel engines: https://en.wikipedia.org/wiki/List_of_visual_novel_engines just pick whichever fits your needs.
There's also CloudNovel. You need to make an account to use it, there's no cool "camera follows mouse thingy" and if you wanna export it outside of the CloudNovel website, you need to buy the exportation (but with a virtual currency, also, there's premium memberships that makes that free).
But hey, it works!