2016’s addictive, harrowing twitch shooter Doom was, aside from the reductive title, pretty much the perfect reboot. Gamers have been subjected to some downright awful series restarts these past few years, and it’s nice to see a developer treat a beloved, historic franchise like Doom with such respect.

RELATED: The 21 Rarest Video Games Of All Time (And 9 Super Rare Accessories)

As per id Software tradition, the release was riddled with Easter eggs, and it actually took the community more than two years to suss everything out. Though some may go over the heads of newcomers, FPS veterans and those in the know will probably crack a smile at each of these Doom 2016 secrets.

Super Turbo Turkey Puncher 3

For all the heavy themes of violence and religion, Doom has never taken itself all that seriously. While it could possibly have been grounds for some darker themes, id Software preferred to put the emphasis on gameplay, and that’s all for the better. That theme continues in 2016’s edition of Doom as the plot is essentially little more than a flimsy reason to string locations and hoards of demons together.

Another example of the game’s less-than-serious tone is the Super Turbo Turkey Puncher 3 arcade machine hidden in the Advanced Research Complex stage. Stashed behind some crates, it’s that same, repetitive hilarity as first seen in ‘04’s Doom 3.

Commander Keen

Before id Software made it big with games like Doom, Wolfenstein, and Quake, they were known for their smaller yet equally beloved series of PC-exclusive action platformer games. A far cry from what we know id Software for these days, the Keen series isn’t exactly likely to make a return sans a few re-releases or remasterings.

In fact, 2016’s Doom seems to imply that Keen may be dead in a less-than-figurative sense, as a skeleton wearing Keen’s iconic helmet can be found in a cave in Kadingir Sanctum. One Redditor pointed out that this may act as an homage to how much platforming is in this new rendition of Doom, but that’s likely thinking just a bit too far into things.

Demon Destruction

The Commander Keen games are far from the only examples of the wider video game world referenced in Doom 2016. In Lazarus Labs, explorative players found that interacting with one of the monitors in Olivia Pierce’s office activated a hidden mini-game. A match three game very much in the vein of something like Bejeweled or Candy Crush, it’s a fun little distraction—and a hidden objective—in a game otherwise primarily focused on slaughtering hellspawn.

Related: Bethesda's 2019 E3 Showcase: Doom Eternal Confirmed And 'Much More' Planned

It’s far from the most robust Easter egg, but it’s guaranteed to hold player’s attention for longer than Super Turbo Turkey Puncher 3. Perhaps, had Olivia spent a little less time playing Demon Destruction and more time doing her job, things may not have played out as they did.

Iron Helmet

Do you get to the Necropolis very often? Oh, what am I saying—of course you don’t! As it turns out, there’s a small reference to another classic Bethesda title deep within Doom’s later stages. A skeleton bearing the unmistakable iron helmet synonymous with The Elder Scrolls V: Skyrim can be found in a cave deep in the game’s famous netherworld.

It’s important to note that this isn’t necessarily the Dragonborn—multiple NPCs can be seen wearing very similar helmets—but it’s impossible to say for sure. What’s more, there’s literally an arrow sticking out of the poor fellow’s knee, which is a less-than-subtle reference to that oft-repeated meme.

Sean Bean

Anyone with even a casual familiarity with Hollywood actor Sean Bean will know that he has an uncanny propensity to be written off of every project in which he participates. From Goldeneye to Lord of the Rings, his characters never seem to be all that long for this world.

The same seems to be true in the Doom universe, as well, as his name can be seen among a list of names initially included in a casualty report right at the beginning of the game. Interestingly, the dev team wasn’t referencing the actor here, he merely shares a name with the game’s Lead Campaign Producers, the man to whom they were actually referring. Talk about a weird coincidence. No word on if the actor will be appearing in the upcoming Doom film.

Doom Guy’s Face

While the first two Doom titles were eager to show off the protagonist’s every facial expression, that feature has oddly gone missing in the two subsequent mainline franchise releases. However, the Doom Marine’s face can be glimpsed under very specific conditions in Doom 2016.

If the player dies by explosion in any of the hidden retro Doom levels scattered throughout the game, the player model’s head will pop off, revealing a rather strange, pixelated expression. It’s an odd Easter egg, but it’s nice to see that, no matter how advanced graphical technology becomes, Doom Guy will always look like that.

Soul Cube

These days, id Software’s 2004 effort Doom 3 feels a bit like the black sheep of the franchise. A graphical powerhouse capable of melting GPUs back in the day, there isn’t much love for it now. However, the dev team behind 2016’s rendition of Doom certainly hasn’t forgotten it, and there’s a small nod to the title hidden in the Lazarus Labs.

Related: Doom Eternal Is Coming To Google's Stadia

On a seemingly innocuous shelf, players who blasted their way through either the original or BFG versions of the aforementioned early 2000’s title will recognize the Soul Cube sitting there. The Soul Cube was easily the most memorable part of that campaign, and it’s a bummer that it can’t be picked up and used this time around.

Icon of Sin

By now, everyone and their mother knows that id Software co-founder John Romero’s head could be found impaled on a spike behind the Icon of Sin, the final boss of Doom II. What’s more, the reversed speech spouted by the antagonist at the beginning of the encounter can be flipped around to reveal a hidden message from Romero himself.

The same thing can actually be done to the now-dormant Icon of Sin in 2016’s version of Doom. Shoot the massive creature in the center of the forehead with a rocket, and that same creepy, backmasked speech can be heard beneath all of the ambient horrors of the Necropolis.

ShareWare

Replaced by today’s demos and free trials, scarce though they may be, shareware was a method by which developers could both market and spread awareness for their games back in the mid to late 1990s. Players could get their hands on the first section of a game, and, if they liked what they saw, they could purchase the full thing.

It’s a technique which helped some of id Software’s original games to attain such popularity, and they paid homage to it by including an achievement titled “Shareware” in Doom 2016. Players can earn it by putting a SnapMap together, and, given how underused the game’s multiplayer is these days, that may not be a feature with which everyone is familiar.

Authorization, Olivia Pierce

Discovered just a few weeks ago, this Easter egg was confirmed as the final piece in the puzzle that was Doom 2016’s Easter egg hunt. An ingenuitive listener examining the seventh track of the game’s OST, titled “Authorization, Olivia Pierce,” and found that a hidden piece of dialogue can be heard by playing with the pitch of the song.

Around fifty seconds into the track, attentive listeners may be able to hear Pierce saying the words “You could not have saved them anyway, you know.” That’s an extremely well-hidden little egg, but, given how little interest the Doom Guy showed in Olivia or the plot of the game as a whole, it’s unlikely that he would ever have cared about her secret message.

NEXT: Board Games Based On Video Games That Are Actually Worth Buying