Triptych: It's The Most Burtony Time Of The Year

"Nightmare In Pumpkinland" by Alison Acton

"The Curse" by TheGeekGallery

"Beetlejuice Genuine Ale" by Atlas Specter

Okay, so Castlevania II is not related in any way to Tim Burton. It's still spoOOOOoooOOOOoooooky.

Triptych: No Monsters In The Projection Booth!

"Gremlins" by James Stayte

"Part of This Complete Breakfast: Gremlins" by Ian Glaubinger

"Mogwai" and "Gremlin" by Brad McGinty

Triptych: Cowabunga

"Shredder's Last Stand" by Justin Currie

"Cowabunga" by Nacho Diaz

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"Teenage Mutant Ninja Tortoises" by Darren Rawlings

Triptych: Doukutsu Monogatari

"Cave Story" by BlackBookAlpha

"Cave Story" by David N.

"Cave Story" by Nick Savino

Triptych: Welcome To The Nightosphere

"Doom Time" by Cheese Demon

"Ghostbusting Time" by Jade Boylan

"This Musical Life" by FatalDose

Triptych: Gravity Falls National Park, Oregon

"Gravity Falls: Pseudo Pixel Art" by EvilGlen

"Gravity Falls National Park Poster" by Jonathan Eveson

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"Gravity Falls Map" by Mark Mak

Triptych: Gamer's Love

"NES" by Walter Newton

"Gamer's Love" by biticol

"The Coin-Op Kid" by Neil Hanvey

Triptych: Yo, Mr. White!

"Walt and the Bad Breakers" by Joe Spiotto

"The Emperor" (t-shirt) by Adams Rebouças Pinto

"Breaking Bit" by Pablo Cialoni

Triptych: So Apparently, This Is A Thing

"Mega Pals" by Harebrained

"Steam Boat Megaman" (t-shirt) by Sam Chapman

"Mr. Blaster: Retro Megaman" by RobotsAreRed

Triptych: You Are Incompatible. You Will Be Deleted.

"Doctor Who Poster" by justonescarf design

"Day of the Dalek" (t-shirt) by Olipop

(Click for full-size)
"We Will Survive" by Paul Hanley

Triptych: Those Darn Koopa Kids

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"Super Koopa Cousins" by Scottland Willetts

"7 Evil Ex Koopa Kids" by PixelMagus

"Koopaling's Totem Hokum" by Hugo Henriques Pereira

Were they cousins? I have no idea. I always assumed they were siblings.

Triptych: Island of Adventure

"Adventure Island" by Classy Raptor

"BMO Entertainment System" (t-shirt) by Snellby

"Adventure Tetris" (t-shirt) by Avokes

Triptych: Sugar Skulls

"Day of the De-Adventure Time" by Ewan Warburton

"Jack do los Muertos" by Synaptix

"LV-426" by Jonathan Koshi

Triptych: Go, Team Winchester!

"Demon Hunter's Crest" by Arinesart

"The Winchester Bros." (t-shirt) by Brian J. Smith

"SPN and The Little Dipper" by Addict-Se
(Also check out Addict-Se's awesome Gravity Falls\Slenderman mashup)

Triptych: Aerith Got A Raw Deal

"Final Fantasy VII Pixels" by William Dickeson

"Final Fantasy VII Poster" by David Goh

"Don't Step On The Flowers" (t-shirt) by Barefists

Triptych: Your Inspector For Today

"Inspector Spacetime: Day of the Blorgons" by Jonathan Eveson

"Trust The Inspector" by Winter Artwork

"Greendale Masters" by Steverino11

Triptych: Chozo DNA

"Brinstar Babe" by Brendan Corris

"Hunt The Huntress" (t-shirt) by Kari Fry

"Digitized Samus Aran" by PixelBlock