Best Boss Ever: Common consensus among the endgame fanbase indicates the Twilight Archmage to be this.
Broken Base: On many, many many things. Pets, 16-bit sprites, using Reddit as a primary communication platform... the list goes on.
Possibly the biggest one is dragging and leeching. A common tactic for poorly-equipped or low-level players when entering a dungeon is to sit in the entrance to the dungeon and wait for the better player to reach the boss room, where they teleport to the boss to try and get some of the loot. In response, some players will collect a large group of enemies and kite them on top of the leeching player, often in far too large groups for the leeching player to deal with. Whether either of these attitudes are justified is a common hot point among fans, so bring it up at your own risk.
Dude, Where's My Reward?: The limited Belladonna's Garden has a rather difficult boss and infamous insta-kill flowers that are hard to spot...but the rewards are only T9 weapon reskins, with a minuscule chance of getting a skin.
The Woodland Labyrinth is infamous for invoking this. You must go through a Brutal Bonus Level with a confusing, maze-like layout, fight through hordes of extremely deadly enemies, avoid numerous invincible turrets, and defeat a 3-stage Sequential Boss with brutally powerful attacks and a tendency to stack shots. And the reward for all this...is a single Vitality Potion, with a minuscule chance of getting a top-tier weapon that could be gotten from an easier dungeon like the other Epic Dungeons, and an even smaller chance to get the Leaf Bow, which for all its purposes is an Awesome, but Impractical weapon most of the time.
Fanon: Pretty much all of the game's lore is this.
Game Breaker: The Spider Den dungeon formerly made it too easy to level up, allowing a player to increase from level 1 to level 10.
The best healing spell also used to fully heal everyone on the entire map. One priest could cast it two or three consecutive times without mana potions.
Pets, or at least high-level Heal/Magic Heal pets. Levelling the Heal ability to level 100 (The highest possible) results in the pet healing you for 90 HP... every second. This means that many situations that would previously have been lethal are now cakewalks due to enemies simply being unable to kill you faster than your pets can heal them. Magic Heal is similar, if slightly less effective, healing you for only 45 MP per second, but this is still enough to let every single character spam their ability to no end.
As a direct result of pets, sword classes (Particularly the Warrior and Knight) have become this. Their dangerously low range in exchange for incredible offensive ability previously made them a high-risk high-reward class, with their high defense only allowing them to spend a short time within effective sword range. With pets healing them and refilling their magic, this changed; Knights can now permanantly lock enemies in the Stunned status rendering them unable to fight back the second they close to melee range, made easier by the constant healing, and Warriors can permanantly buff themselves with the Armoured status by using the untiered Helm of the Juggernaut, skyrocketing their Defense to levels that, augmented by the high Heal power of pets, they can simply ignore every single shot that comes their way, even the 200+ damage ones.
The first is the derailment caused by pets- a fully maxed Knight or Warrior can basically ignore anything shot at them until they reach sword engagement range, and then sit there until their target is dead, being healed for any damage they take by something healing more than a Priest could.
The other is just a simple evolution of the game's playerbase. When the game was in its golden age, the devs were balancing content around the expectations of there only being 4-6 maxed players in a realm at one time, the majority of the players spending time in midlands or highlands levelling up.note This is, among other reasons, why the Godlands are so small compared to the rest of the realm Now, realms in popular servers are unlikely to dip below a population of 60-70, the majority of which will have at least one stat maxed. This sheer imbalance leads to even the strongest events and enemies being steamrolled in a matter of seconds- about the only things that you can reliably expect to live longer than half a second are the Avatar of the Forgotten King, the bosses from the Shatters, and Oryx the Mad God 2. And even then in a full realm you won't see them live longer than a minute or two, most of which will be their invincibility phases.
Goddamn Bats: The bats in the Manor of the Immortals; they inflict the incredibly annoying Confused status, making it highly likely you'll stumble right into Nosferatu.
Heroic Lineage: A couple of achievements imply that every new character is the child of the former character, or at least otherwise related, and thus that 'Fame' is the leveragable prestige of the family name.
Idiot Programming: The client-side of the game is programmed in AdobeFlash, making it par for the course. However, there are a number of issues that arise due to the nature of the game (Realm originated as a 1-month contest entry) that have at best been glossed over, the main one being the complete lack of database integrity or client-side security; this is why hackers and dupers are so prevelant in a game with a team dedicated to banning them.
Junk Rare: Some intentionally useless UT items, such as the ones from the Battle of the Nexus. No actual use, but look pretty cool.
Similarly, some tiered reskin items such as the Belladonna's Garden reskins or the Haloween reskins. No difference from regular tiered weapons save what they look like. Averted by the Winter reskins, due to dropping continuously for over a year.
Free itens pls. note The stereotypical begging of a player who can't actually play the game and is likely to just get themselves killed with the items by running headfirst into danger. If you use these words seriously, expect a lot of mocking from other players.
Lel xD. note The fanmade Catch Phrase of the Knight, due to the community deeming him such a low-risk high-reward class that all Knight players are now labelled as immature numbskulls.
Buff Hydra. note The T13 Hydra Skin Armor is supposed to be the highest tier leather armor, but is outclassed in nearly every way by most of the other UT armors like Coral Silk or Spectral Cloth. This has left fans begging for a buff for a while now, in often hilarious ways.
Now an Ascended Meme, as for April Fools DECA buffed the Hydra Skin Armor temporarily. note By "buff", we mean they gave it a +1 MP bonus...
The drop rate of some of the White Bags is so notoriously low (particularly the Wand of the Bulwark and the Shatters/Event Whites) that it's often poked fun at on the subreddit, such as people saying Bulwarks are an extinct species.
Yin Yarns Barn (in Why the Warrior is Stupid): "I'm not even going to talk about the Helm Of The Juggernaut. Why should I? The helmet only drops if the temperature outside is exactly 67 degrees Fahrenheit and the stars are all aligned in the precise order they need to be."
The Avatar of the Forgotten King. It has extremely dangerous attacks, several phases, and lethal minions, which is standard for an event boss. However, the thing has 500,000 HP, more than any other boss in the game. It also has 90 base DEF, and has the Armored effect on at almost all times, resulting in 180 DEF, which in turn heavily reduces the damage you can do. Combine the two and you have a solid reason to why this is the game's resident Marathon Boss. Unless someone has the Shield of Ogmur, expect to take a lot of time trying to kill it.
The Jade and Garnet Statues. They aren't too bad, having similar stats to most event bosses, but they possess an One-Hit Kill dash attack that can easily catch players off guard. The only warning is the Statue using it flashing red, and the dash can run over people that are almost off the screen. While the warning is fairly easy to see, the risk of teleporting to them and getting instantly butchered is high and has caused players to take safety measures. Needless to say, the dash alone has earned these bosses a special place in Oryx's arsenal of Event Bosses.
Bes, Nut, and Geb in the Tomb of the Ancients. Each of them brings something different to the table, Bes being the Mighty Glacier with high HP/DEF and attacks that can stun and break armor, Nut being the Support Party Member who can heal the others and fire countless status-inflicting shots, and Geb being the Long-Range Fighter with rapid, wide-area barrages of extremely dangerous shots and bombs designed to shred players instantly. They each provide a unique role in the battle and strategy is key to defeating them. Unfortunately, in a "public" tomb, coordination is almost nonexistent and 99 times out of 100, the plan for killing them goes out the window and turns into "shoot anything that moves". Which ends up leading to a boss battle a lot harder than it should be, which is especially alarming considering each of the bosses were already extremely hard to begin with.
And of course, the game's resident True Final Boss: Oryx the Mad God 2. Packing 75000 HP and 60 DEF, he is equipped with a brutal long-ranged shotgun of multicolored stars that deals enough damage to instantly shred any class in the game and also inflicts Confused, Slowed, Blind and Quiet. Since he spams this shotgun constantly, it is almost impossible to get close to him, and is made even harder by the fact that he constantly spawns Henchmen of Oryx that can confuse you into his shots, who also spawn their own minions. Oh, and he also employs omnidirectional attacks and can spawn Monstrosity Scarabs to bomb you. It somehow gets even worse when he Turns Red and begins to chase players while utilising nigh-unavoidable attacks that severely cripple attacks and abilities (they Quiet for 20s and Weaken for a whole minute). He has earned a nasty reputation for murdering countless 8/8 players and is well deserving of his title as Final Boss.
The Scrappy: Kabam!. They weren't too badly disliked after first acquiring the game from Wildshadow Studios, mostly because the game would likely have been shut down without that. Since then, aside from a few good moves such as the Haunted Cemetary and Davy Jones's Locker they have done very little to actually support the game; the Epic Dungeons are simply much harder versions of the three easiest dungeons in the game, The Shatters was designed by one of the forum-goers, the Lair of Draconis and the Ice Cave both took forever tocome out, they frequently break promises made to the playerbase, do very little to fix glitches or shut down hacking, have very poor support (often not even reading the tickets they get sent), and made a number of Pay-to-Win measures.
Most recently, they left the game completely untouched for six months. An MMO with no updates, little word from the devs, rife with hacking and cheating, a seasonal-themed Nexus that rapidly became outdated, and no word on if the game would continue to be worked on. Eventually, one of the G Ms announced that the entire dev team had been pulled away from the very active MMO to work on mobile games and "would be working on the game in the future." Two months after that and the only activity is from that same GM, who is using recycled events to attempt to breathe some life into the rapidly-ailing game. Needless to say, this has not endeared Kabam! to the game's fans.
Win the Crowd: DECA Games won the crowd just by buying the game from Kabam!. They then followed up with a month-long celebration, just to rub it in.