I'm not familiar with the original game, so I can't comment on how this episode relates to it, but in relation to the show as a whole, this episode doesn't do much to move the series forward. Only half of this episode really "works," but the parts that do really, really work. I found the jokes genuinely funny (which is rare for me with anime), and seeing Kanji's sexuality become a topic of discussion was genuinely interesting to see (though Hanamura and Narukami's treatment of him was questionable at best. I hope they explore this in later episodes).
As for the ending, where the protagonists gather to swim in the river, I honestly can't tell if this is a satire of the infamous "beach" filler episodes so popular in anime series, or if the intention really was to pander to the audience. Regardless, it left a bit of a bad taste in my mouth.