Touhou Mother (InstanceTopic, 22)
From Compile Worlds
Touhou Mother is an RPG Maker 2000 fangame which is a crossover between the Touhou and Mother/Earthbound series.
Just like any Touhou doujin work, it's filled with references and memes. Even to an obscure fan character from a fangame that never got made.
Its main references (outside of Touhou and Mother) are to Pokémon, Castlevania, Cave Story, Yu-Gi-Oh and Metabots. There might be more...