Splatoon Island - Splatoon Island

Also:

Average large internet websites on April Fools: "Haha, look at our goof, we changed a few things with the layout/did a fake feature thing which took us a day or 2 to put up, gottem"

Mike Inel almost all by himself: "I'M MAKING FUCKING TOP-QUALITY PATREON-FUNDED HIGH PRODUCTION VALUE 3D ANIMATION THAT'LL MAKE YOU WISH IT WAS ACTUALLY REAL JUST FOR A PRANK AND NOBODY CAN STOP ME!"

And the award for this years April's Fool Joke go to… Mike Inel