Good afternoon. I've had this idea for a while, but I never had time to write it down here. I hope it's not too late to create one. It might even exist, but I didn't see the Easter egg. I'd like a small crossover with the game Neko Odyssey - a fleeting encounter on the street in the city, a meeting at a bar, sharing photos with each other, so the other photographer would be shocked but still praise them from an artistic standpoint. Or a post on a computer channel, perhaps not the main character. Or maybe this new character would be added to the trip to Japan. Or the craziest thing - sex with her; I hope she's 18 by now, according to the story.
While more crossovers and references would be nice, I think there are couple things to keep in mind.
- SFW developers are not going to collaborate with NSFW developers. In your example Sunny Syrup would be risking a lot on their reputation having their character portrayed in this way.
- There maybe scope for crossovers with other NSFW developers, but this is normally quid pro quo "you can use my character if I can use yours." So you are more likely to see actual characters from other games where Kal has working relationship with said developer.
- You most likely to see (and there already is) crossovers from other Arvus Games like Roundscape, Below Sunshade, Arenus...
- That is not to say Kal cannot take inspiration from other games when creating characters and events though... so you never know...