Before Call of Duty and Halo dominated the first person shooter scene, before Half-Life revolutionized video game storytelling, and before Quake and Doom wowed PC gamers with their moody, gothic aesthetics (not to mention revolutionary technical enhancements like, say, stairs), there was Wolfenstein. Wolfenstein 3D wasn't the first FPS - that honor goes to either Maze War or Spasim, depending on who's telling the story - but it was the first to really catch on with the public.

In fact, without Wolfenstein 3D, it's arguable that first person games as fans know them wouldn't exist. Today, the game's fifth sequel (barring an expansion pack or two), Wolfenstein: The Old Blood, hits, serving as both a stand-alone expansion and prequel to last year's installment, Wolfenstein: The New Order. The Old Blood's developer MachineGames seems keenly aware of the franchise's place in history, and the game's designers have pulled out all of the stops to make sure that fans do too. As observant players noticed, Wolfenstein: The Old Blood is crammed full of Easter eggs that honor Wolfenstein's storied legacy, and pay tribute to some of the games that Wolfenstein 3D inspired.

Some of the Easter eggs are obvious. In the first level, players can look out of the window of a tram and see posters taped to the wall that depict scenes from Wolfenstein 3D. Similar to an Easter egg found in Wolfenstein: The New Order, players who actually want to try the classic title for themselves can use a bunk bed to enter a surreal, pixelated remake of the original game.

Other Easter eggs require a little bit of history to recognize. Doom and Quake are considered Wolfenstein 3D's immediate successors, and MachineGames pays tribute to both in The Old Blood. One of Doom's iconic Cacodemons shows up as a desk toy, while Quake 3's rocket launcher dangles from hero B.J. Blazkowicz's keychain during the The Old Blood's opening scene.

Finally, nods to a few other games wormed their way into Wolfenstein too, mainly honoring other titles from The Old Blood publisher Bethesda. Skyrim's Dragonborn helm gives BJ an armor boost, while a vending machine serves Nuka-Cola, the most popular soda in the Fallout series.

Neither Skyrim nor Fallout are Wolfenstein 3D's direct descendants: the Fallout franchise started as a series of isometric RPGs by Interplay Entertainment, while Skyrim builds on the foundation established in The Elder Scrolls II: Daggerfall; Daggerfall director Ted Peterson claims that it wasn't influenced by its contemporaries, claiming that games like Doom "weren't very interesting." Still, Bethesda raised Wolfenstein from the grave with The New Order; at this point, the company is just as much a part of the Wolfenstein 3D legacy as id Software, the game's original publisher. As such, in-game tributes to the publisher's other hits don't feel that out of place.

Wolfenstein: The Old Blood is out today, May 5, 2015, for PC, PlayStation 4, and Xbox One.

Source: Kotaku, TheRealSpoons, Daniel Mortensen