Cameos and References
This is a list of games and other media that have referenced Cave Story in some way or form. This page is still a work in progress and is by no means exhaustive.
Curly can be unlocked as a playable character in 1001 Spikes by obtaining 30 golden skulls. She is equipped with a Booster 2.0 and her trademark machine gun.
A statue of Balrog can be found in a room behind that ledge to the right of the fire bomb enemy in the Clock Tower. You will need the Wing Boots to reach it.
The Polaris, a reference to the Polar Star, can be unlocked by completing the Hollow 20 times.
The robot hat has a 0.4% chance to drop from Piranhas or Angler Fish in Terraria. It is a reference to the hat worn by Quote in Cave Story.
Paintings of Quote and Curly can be found on the second floor if you can be distracted long enough from trying to poke cats.
Quote is available as a playable character in the Good Friends Character Pack for BIT.TRIP Runner 2.
"Remember, Pit, you won't be fighting alone out there."
"You're going to send me a machine-gun-robot girlfriend?"
From the opening lines of the Powers
If you click on the SNES controller in the main menu of the Steam release of "Indie Game: The Movie" then you get an indie game character mix and match game.
on the character select screen to select either Quote or Curly as your character.
I Wanna Kill The Guy
Curly is used as an optional dance off boss in chapter 3 of IWKTG v.052.
The Suite Life on Deck
The start point from Cave Story is shown in an arcade machine in season 2 episode "Goin' Bananas".