Nippon Ichi will release Cave Story 3D in Japan on July 26. What took so long between releases? It might be adding in new retro game collaborations. Famitsu magazine reports the old-school style action game has crossover content from three retro games:

Crazy Climber

Ikki

Dragon Slayer

Details on what the collaboration entails have not leaked online yet. Cave Story 3D already has a Nippon Ichi item, the Prinny cap, which you can get in a secret area.