Hi Sora, yeah I was definitely inspired by 90's cartoon aesthetics, like Johnny Bravo, The Tick and Fairly Odd Parents. These are the shows I remember watching in my teens, and found their handsome and stylized characters really appealing. I like to call this style "Nick-Toon Style", for Nickelodeon.
And yeah Nikau was very difficult lol. Once you found the walkthrough and read the answers, did the way you were meant to woo him make you go "Ah haaaa, that's why!" =p