Only three so far. By "event" I mean triggerable dialogue scenes with floating event markers. One is the rescue event with Illusive which has two dialogue branches, there's the Old Woman near the floating hill Altar, and the last is the Alleyway Bar event
which leads to a game over.
The only NPC you can talk to more than once right now is Suzune and her questline is incomplete so far. Illusive you can talk to once and gifts you a weapon, but she can't sell items as of now. Vendetta you can talk with to re-spec your character.
There are a few witches you can rescue around the entire game. Mostly around the initial areas, but there are some in the latter parts as well.
Check my map for the other mini-events.
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