I think that's probably the best way to preserve the tone you were going for and make minimal changes to the plot, yeah. Change the lines about him being top of the class to him being middle of the pack or barely graduating or introduce a twist later that he was getting behind the scenes help and never realized it because he's kinda a shitty, easily distracted detective, although if you do that one you should probably foreshadow it a little bit, maybe just a few throwaway lines mentioning, say, his favorite professor who helped him a bunch or something like that. Like I said, there's nothing wrong with the game's tone or with him being kinda a goofy, horny dumbass, but there is something wrong if the rest of the game's writing/world doesn't realize he's a goofy, horny dumbass. Unless it's a whole world of goofy, horny dumbasses and he's comparatively a genius, but that doesn't seem to be the case. For one, Misty seems a lot more competent than him and Pam was able to bamboozle him with just a bit of cleavage. Again, not a problem for him to be easily misled or manipulated, but it is a problem for him to be a competent detective who's easily misled or manipulated, change one of those two things and the problem goes away. And I think the other people in the thread and I are over-emphasizing his incompetence, partly because it's really frontloaded in the plot. He does eventually start putting things together on his own a little bit towards the end of the case, albeit way, way later than the evidence should have led him to, which is fine if he's going to be a bad detective who gets better as the story goes on.
Overall, though, this one complaint is kind of the only one I have. Game's writing was mostly funny and charming, I like the artwork and the characters, and the scenario seems like it'll be fun to see expand. I just didn't enjoy being told how competent a detective I was playing and then watching him be really slow solving the first case. I think the only other thing to keep in mind is how you wrote the Anna plot line to be kinda romantic, in a story where your main character is, presumably, going to be sleeping around a lot. Keeping that romantic tone is fine, but it may be a good idea to establish that an open relationship is something she's okay with, or the main character's going to come off as a scumbag (or, again, you could not establish that and have him not even realize he's cheating on her if you want to play up the oblivious comedy angle, but I don't think that's the best solution tone-wise).