Adaptive Ability: Jee-Han's Gamer ability allows him to acquire and improve skills based on his actions. Doing normal actions such as working out or studying grants him basic EXP, while using an acquired skill increases its level. Extensively using a specific attribute such as Intelligence also has the chance to improve it.* Awesomeness by Analysis: Part of the comic's appeal is Jee-Han figuring out not only how do his powers work, but also how to min-max themto gain an edge.
Badass Grandpa: Shin Sun-Oh is so strong Jee-Han can't even see his level.
Batter Up: Jee-Han's first weapon of choice. He tries out several others later, eventually settling on a spear.
Combat Tentacles: Looking for a way to lock down his opponents, Jee-Han created the Mana Rope ability, which can act as this.
Death Seeker: Sung-Ah has really been pushed into depression by how burdensome her curse is. She's perfectly fine with letting the kidnappers sent by the Mana farm to catch Jae-Han get her while he gets away because she's so ready to give up on life. The only thing that's kept her alive this long is most likely her father's dedication.
Deflector Shield: The Mana Shield ability works like this. With a little grinding, Jee-Han might be able to make it permanent.
Drama-Preserving Handicap: The author's answer to make sure that Jee-Han doesn't become such an obvious Game Breaker thanks to his Gamer ability is to make sure that his Wisdom stat remains relatively low so that Jae-Han doesn't make the necessary, or completely correct, decisions regarding how to power up his abilities. For example, his lack of Wisdom causes Jee-Han to rush into things without fully thinking the process through such as suddenly dumping all his extra stat-points into Intelligence despite knowing that it would help build his judgement, and thinking-process, if he put points into Wisdom.
The Empath: Jee-Han is an example, after a fashion, thanks to his Observe/Inspect ability also revealing the target's emotional state.
Empowered Badass Normal: It's possible for people to develop abnormal powers through training. Jee-Han realizes that one of his longtime best friends is like this based on his title and unusually high level.
Evolving Attack: Much to Jee-Han's delight, his Spinning Mana Arrow doesn't just raise in power as he trains with it, but also allows him to shoot multiple ones in a single cast, creating a small barrage.
Gay Option: In the What If? extra where the main character's life becomes a dating sim, Shin Sung-Il is on the list of datable characters.
Glass Cannon: Sung-Ah's stat page seems to point towards this. She has abysmal stats in vitality and strength, pointing to a very frail body, but has even more Int(elligence) than Jee-Han, along with very high Wis(dom) and good Luck, all indicative of a heavy-hitting mage. Justified, since she's been cursed since birth with an ailment of some sort that drains her life force.
Foreshadowing: As expected, a few chapters after Jae Han is warned about the possibility of Mana Farms coming after him in order to exploit his powers, a pair of people from the Abyss who capture people and sell them to the farms appears and comes after him.
Hard Work Hardly Works: Played with. Jee-Han can instantly learn new techniques by using a skillbook, then immediately use them proficiently, whereas normal people would have to struggle with the learning process then train with the skill to gain a similar level of proficiency. A wonderful example is Jee-Han learning the Yunhon Soul Recovery technique, which none of the Chunbumoon knew because they were still researching its theory. He proceeded to use it to accelerate Sung-Il's healing process from one month to one day. However, Jee-Han's skills all have levels of their own, and he has to work his butt off to strengthen them all the same. He also has to actually perform actions to gain new skills on his own, and Sung-Il reminded him that he still needs actual experience to be able to use the skills effectively, so he still trains with Sung-Il in order to get just that.
Healing Hands: Jee-Han when using the Yunhon Soul Recovery technique.
Heart Is an Awesome Power: While it at first seems like Jee-Han missed a chance at some awesome superpowers because his love for games gave him a gamer ability, we later find out that it allows him to learn incredibly powerful techniques in meager amounts of time, and when the mechanics of it are exploited properly, he can very quickly become a force to be reckoned with. They also realize that for his ability to work the way it does, the world literally has to conform to it, meaning that he's technically a member of the rarest and most powerful class of natural ability users. To put it simply, in a world populated by generic tanks, lightning bruisers, and beam spammers, he is a reality warper.
Hidden Depths: Jee-Han can't see his mom's level. This is indicative of very powerful characters; the only others he can't see are Badass Grandpa Shin Sun-Oh and Sung Ma-Hyun, one of the big cheeses in the underworld's Black Market.
How Do I Shot Web?: The first few issues mostly deal with Jee-Han learning how his new abilities work.
Hyperactive Metabolism: Lampshaded. Food heals HP, so the main character responds to a particularly damaging attack by immediately pulling some bread and milk out of his Hyperspace Arsenal and frantically stuffing them down his mouth as fast as possible... in the middle of a fight.
Also justified, because eating does in fact heal him.
Idiot Hero: With a wisdom-dumping stat sheet to prove it! He's actually not usually that bad (he does a good job figuring out his own abilities, at least), partially because he has the advantage of a power that recontextualizes absolutely everything into the one context he's intimately familiar with.
Might or might not be a case of Misapplied Phlebotinum from chapter 47 onwards: because his intelligence is high already (and difficult to grind) and skills can be trained through grinding, he realizes it's more efficient to dump his stat points in INT and grind the rest through training, earning him a point in WIS for wise decisions. On the other hand, he hasn't even used his two potentially most powerful skills - Life Drain and Telekinesis, which could be enormously powerful both individually or when combined with other skills (for example his Spinning Mana Arrow or Mana Shield) - and seems to have completely forgotten about the ultimate Chunbumoon skill he could learn with 90 INT. He also visited the Auction only once, and hasn't even considered buying more skills there, not even other elementals. He thinks some things through quite thoroughly, while completely missing out on some of the most obvious options.
I Know Kung-Fu: Jee-Han when he learns the basic Chunbumoon's martial arts techniques.
It's A Small Net After All: It takes less than an hour of research for Jae Han to find the website that the Abyss Auction works through.
Irony: Despite how Jae-Han's obsession with games is mocked, along with his gamer ability (before they realize how much potential it has), some of the characters who appear later do look like RPG characters.
I Want Them Alive: In chapter 34, a pair of what are essentially human traffickers with superpowers appear with the intent of kidnapping Jae Han and selling him to a Mana Farm.
Knowledge Broker: Along with goods and lives, the Abyss Auction deals with information.
They also deal in rare objects that can be found in the Abyss. Poong Sae-Young warns Jae Han to be especially careful after hearing about him because if they discovered more about his ability, they might want to abduct him for it, or for a Mana Farm—where Ability users are held prisoner and have their mana siphoned to be bought and sold.
Level Grinding: Han Jee-Han does this constantly, both to increase his overall level and the levels of individual skills.
Masquerade: Enforced. If you break it, the world itself will kill you. But you can use it to make a living off of it.
Money Spider: One of the in-universe strangest aspects to Jee-Han's ability. Usually the monsters encountered in Instant Dungeons don't drop anything since they're just dead spirits given form. However, after fighting boss monsters Jee-Han gets things like money, skill books and healing potions - these last worth a lot of money just by themselves. Essentially, he's creating something from where there really should be nothing.
Ms. Fanservice: Poong Sae-Young, Shin Sung-Il's older cousin. The most she has ever worn is a T-shirt and Hot pants.
Mundane Utility: Jee-Han is able to improve his passive dish washing skill.
New Transfer Student: Kwon Shi-Yun suddenly transfers to Han's class not long after he encounters her, along with Hwan Sung-Ah. For extra comedy, Hwan Sung-Gon transfers as a teacher.
Obstructive Codeof Conduct: The Interference Law prevents those with powers from affecting the real world with the penalty of death. The extent of the law is rather vague but it basically boils down to 'don't do anything too obviously supernatural'.
Our Zombies Are Different: They come off as the typical slow zombie. They're actually spirits of the dead given shape inside an Illusion Barrier. Meaning that they don't have physical bodies and simply dissolve after being destroyed leaving nothing behind.
Except when they're destroyed by Han, they drop items due to his ability.
Phantom Zone: All ability users have the ability to create 'Illusion Barriers' where they can fight without affecting the real world (or breaking the Masquerade.)
Played with. He comes from a wealthy family of martial artists, but they're very old fashioned and value discipline so he doesn't have many of the fancy electronics or perks that come with being rich.
RPG Mechanics Verse: The Gamer ability turns Jee-Han's life into this. It's a weird example, since the setting as a whole apparently isn't one; it's more that his superpower is to interact with the world as if it were a game.
Something Only They Would Say: Jee-Han convinces his best friend, Shin Sun-Il, of who he is... by making a ridiculously bad Star Wars joke while Shin Sun-Il is choking him and demanding to know his real identity.
The same happens a bit later with Sae-Young, under basically the same circumstances. He convinces her that he is the real Jee-Han by...revealing he knew she wears black lace silk panties since several years ago,note He was about to say 2nd year of either Junior or High School, but got interrupted mid-way by a raging woman. something only he would know since he went into her room once without her permission.
Super Power Lottery: Jee-Han is a natural ability user, someone who was gifted with a sort of supernatural power by chance. Natural ability users gain abilities based on what they love or are passionate about. Thus, Han's love for RPGs is why he has powers based around RPG mechanics.
In addition, while both people that have found out about Jee-Han's ability laughed at it, almost all fans realized how absurdly powerful Game Breaking Jee-Han's ability is. He is practically immune to any damage that doesn't kill him, recovers his full health extremely quickly, and can pretty much learn ANY ability he wants. He could also potentially raise one of his stats such as Strength to god-like levels incredibly quickly. To put numbers on it, when the story began, he had a Strength of 10, and raised it to 15 with his first level-up. Since then, he has gained 3 levels, and could put 15 more points in Strength, if he wanted to. That means that in less than a month, he could have TRIPLED his base Strength.
He later finds out that he's what's called a late bloomer. Some natural abilities are powerful to begin with. Late bloomers start off weak, but can become infinitely stronger through training—with no limits.
The Worf Effect: One of the strongest people Jee-Han knows is his longtime friend from school, Shin Sun-Il, who is actually a level 25 acquired ability user . The man in the black suit easily bests both him and his 2 brothers, and lands him a projected month-long recovery time... Which Han cuts down to a day by learning one of his clan's most effective healing techniques.
Time Stands Still: Illusion barriers can have this effect, though they don't last long.
Unskilled, but Strong: Shin Sun-Oh wants to make sure that Jee-Han averts this. He wants Han to come train with him even though Han insists that he's already figured out how to become exponentially stronger by exploiting his ability. Shin then rebukes him by stating that raw power is useless without skills and experience.
Unusually Uninteresting Sight: Both Hwan Sung-Gon (summoner guy) and Kwon Shi-Yun (red haired girl) transfer into Jee-Han's school as a teacher and a student, respectively, but no one besides Jee-Han feels that anything is amiss. Especially egregious is how no one seems to care about Hwan's MIB style attire.