Gundam Build Fighters
Back in the 1980s, the success of the series Mobile Suit Gundam resulted in an economic boom due to sales of the Gundam model kits, or "Gunpla" dubbed the Gunpla Boom. Years later, with the success of the second Gunpla Boom, special tournaments called Gunpla Battles are established throughout the world to see which customized Gunpla and its builder are the best. These incredibly popular Gunpla Battles culminate in an annual global tournament.

The story of the first series revolves around Sei Iori, a young Gunpla Builder and student who has a dream of becoming the best Gunpla Fighter in the tournament and someday become as good as his father. As the only child, his family owns a small Gunpla shop and his talent is well-honed, however his weak piloting abilities have led him to a series of first-round losses. But one day, he meets a strange boy named Reiji, who helps him out. Reiji gives him a jewel, promising that he will come to Sei's aid if wished enough. Together, both of them will tackle the world of Gunpla Battle and compete in the tournament using Sei's customized Gunpla, the GAT-X105B Build Strike Gundam.

--- This one, along with it's direct sequel, Build Fighters TRY, are, in my opinion, some of the best of Gundam. I like the actual shows, don't get me wrong, but they kinda all have the same message of 'War is bad and if we just talked to one another we wouldn't need it'. While Build Fighters has the message, stated early on, of 'We can take it so seriously because it doesn't matter'.

Gundam Build Divers
In the near future, where the Gundam franchise is at its peak and the popularity of Gunpla is soaring to new heights, a new virtual reality massively multiplayer online game (VRMMO) game called Gunpla Battle Nexus Online (GBN) is made. In Gunpla Battle Nexus Online, players can upload themselves and their Gunpla online through the virtual space and battle with players from across the world. In the game itself, the player assumes the role of a Gunpla Diver, and each year a special tournament called "Gunpla Force Battle Tournament" is held to prove who is the best Gunpla Diver. The story revolves around Riku Mikami, a 14-year old junior high school student and an admirer of famous Gunpla Diver Kyoya Kujo. He and his friends Yukio and Momoka love Gunpla and play GBN together. However, his own life changes as he meets a mysterious female Diver named Sarah as strange events take place in the GBN with the appearance of Mass-Divers. Now guided by his new allies, he forms their first Gunpla Diver group, embarking on epic adventures with his friends and to see who is the best fighter in the GBN world which would soon bring unforeseen forces to gunpla.

---Set vaguely after Build Fighters - or at least a world that HAD the same kind of Gunpla Battles as Build Fighters, Divers is your full-dive VRMMO variant, where you're actually piloting the things. Don't worry, there's no 'If you die in the game you die for real' here. This and it's direct sequal Build Divers Re:Rise , hew slightly closer to proper science fiction, with some good ol' sci-fi themes which I won't spoil, but grant some higher stakes than Build Fighters.

Bofuri: I Don't Want to Get Hurt, so I'll Max Out My Defense
Urged on by her friend, Kaede Honjō begins playing the VRMMORPG NewWorld Online under the name Maple. Not wanting to get hurt, Maple opts to be a shield user with maxed-out defense stats, and continues putting every status point she earns in the game into increasing only her defense level. As a result, she is left with slow foot speed and no magic, but her high defense allows her to endure most hits without taking any damage. This, along with her basic-level creative thinking, allows for her to make unexpected accomplishments in the game, its quests and events. By doing this, she ends up earning all kinds of equally unexpected skills and becomes one of the strongest players in the game.

---The unwieldy title suggests an isekai of some sort, but it's another full-dive VRMMO show, this time about minmaxing and how unbalanced you can become through sheer force of ignorance and committing to a theme. Helped out a little bit by the incompetence of the game's administrators. :)

Angelic Layer
The primary protagonist is Misaki Suzuhara. Despite her short appearance she is a seventh grader who just moved to Tokyo to live with her aunt, Shouko Asami. After arriving in the city outside of Tokyo Station, Misaki watches a battle between two dolls on a big live-screen called Angelic Layer, a highly popular game in which players (called Deus) buy and custom-design dolls known as Angels that are moved by mental control when on a field called the "layer."

Interested in learning about Angelic Layer, an eccentric man wearing a white lab coat and glasses, calling himself "Icchan", encourages Misaki to purchase and create her own angel. She wants the angel to be "a short girl, but strong and happy", and names it Hikaru, based on Hikaru Shidō from Clamp's Magic Knight Rayearth (a manga in Angelic Layer's world). Even though she's clueless about the game, Misaki soon competes in tournaments and is assisted and watched carefully by Icchan.

---Not much more to say about this one except I love it with all my heart, and I'd like more people to experience it. Please, do what you can to find a way to watch it! Also, Misaki is friggin' adorable.

Dai-Guard
On February 24, 2018, in the Northwest gap of the Sea of Japan, a giant creature called a Heterodyne appears and goes on a rampage, destroying a major city and killing countless people before being destroyed itself by a weapon of mass destruction known as an "O-E (Over-Explosion) bomb". In the aftermath, a giant robotic weapon system, code-named Dai-Guard, was developed for the military by the 21st Century Defense Security Corporation as an alternative to the future use of such weapons.

However, no further attacks occur for the next twelve years and the 21st Century Corporation is allowed to keep the useless weapon as a mascot which is managed by Public Relations Division 2. However, during a security exposition in 2030, a Heterodyne attacks and the ill-prepared and unarmed robot is taken into battle by its pilot Akagi Shunsuke.

---If my memory serves, I shouldn't need to talk too much about this one, folks here should already know something about it, but still, in case people don't, here it is!

Gargantia on the Verdurous Planet
In the distant future, humankind has taken to the stars and formed the Galactic Alliance of Humankind. The Galactic Alliance is engaged in a perpetual war with a squid-like alien species known as the Hideauze. Sixteen-year-old Ensign Ledo is a soldier in the Galactic Alliance, piloting a Machine Caliber, an artificial intelligence-automated, humanoid-shaped mecha, which he refers to as "Chamber". After a failed attempt by the Galactic Alliance to destroy an enemy super-weapon, Ledo is knocked into a wormhole and loses consciousness.

When he awakens, he discovers that he and Chamber have been "salvaged" by a rag-tag band of "primitive" human scavengers aboard the Gargantia, a massive fleet of ships on an ocean-covered planet. Chamber tells him that local star charts reveal the planet is Earth, the birthplace of humanity, a place that members of the Galactic Alliance were only familiar with from stories and believed was a myth. Ledo must adjust to the language, culture and lifestyle of the planet, while finding his new purpose in life aboard the Gargantia.

---A series written Gen "The Butcher" Urobuchi, man behind Psycho Pass and Madoka Magica. That alone should tell you enough about both it's quality and some of the possible themes. I'm not necessarily a fan of the mans work - I hated Psycho Pass for Reasons, but I can't deny the man can *write*.

Sword Art Online Alternative: Gun Gale Online
Due to the incident that occurred in VR MMORPG Sword Art Online—where 10,000 players were trapped in the game on launch day—the popularity of VR games has plummeted due to fear of similar incidents. The NerveGear, SAO's VR device, was recalled and destroyed, but with the launch of its successor, the AmuSphere, combined with release of the license-free development support package the "Seed", the popularity of VR games saw a sudden resurgence.

The story follows Karen Kohiruimaki, a university student with a complex about her abnormal height. She begins playing a VR game called Gun Gale Online after it gives her the short, cute avatar that she has always wanted.

--- A side series to Sword Art Online, written by a gun otaku. Much like Build Divers, it's an actually fun spin-off of the main series. Karen's "abnormal height" is somewhere around six and a half to seven feet - Tall for anybody, but a veritable kaiju for a Japanese woman. And no, while I actually did enjoy SAO, that isn't gonna be on this list.

Tengen Toppa Gurren Lagann
Gurren Lagann takes place in a future where Earth is ruled by the Spiral King, Lordgenome, who forces mankind to live in isolated subterranean villages. These villages have no contact with the surface world or other villages and are under constant threat of earthquakes. Selected villagers called diggers are conscripted to expand their homes deeper underground. Simon, a meek young digger ostracized by his peers in Giha village, finds solace in his best friend, an older brother figure who is an eccentric delinquent named Kamina. Kamina encourages Simon to join his gang, Team Gurren, to help him achieve his dream of visiting the surface world. One day, Simon unearths a drill-shaped key called a Core Drill, followed by a small mecha resembling a face called a Gunmen.<4><5> Shortly thereafter, a huge Gunmen crashes through the ceiling and begins attacking the village, followed by a girl named Yoko, who attempts to repel the Gunmen. Simon uses his Core Drill to activate the smaller Gunmen (which Kamina names Lagann) and its drilling-based abilities. He successfully uses it to destroy the larger Gunmen and break through the ceiling to bring him and Kamina to the surface world.

--- Do I really need to say anything more? If you haven't seen this, you've at least heard of it.

SSSS.Gridman
The story focuses on Yūta Hibiki, an amnesiac first-year high school student living in the fictional Japanese city of Tsutsujidai. He meets the Hyper Agent Gridman in an old computer, who states that the boy has a mission he must fulfill; Yūta sets out to find the meaning to those words and his memory loss. The sudden appearance of kaiju eventually changes the usual dynamics of Yūta and his classmates. Yūta is able to merge with Gridman to fight kaiju, but after the kaiju attack, people's memories are reset and those who die are forgotten. As the "Gridman Alliance", Yūta and his friends now seek to stop the kaiju and uncover the truth behind the disappearances, with assistance from mysterious friends of Gridman who can transform into weapons that Gridman can use in combat.

--- Ever seen Superhuman Samurai Syber Squad? That was Gridman. Gridman was originally meant to be an Ultra series, but was rejected and became it's own thing. This is SSSS.Gridman. I can't really say much more than this that isn't a spoiler of some sort, but it has a....companion? series called SSSS.Dynazenon, which I haven't seen enough of yet.

Stellvia of the Universe (Stellvia)
The series takes place in the year 2356 A.D., around 189 years after a worldwide catastrophe had wiped out 10% of Earth's population. To keep track on all space activities, mankind has built numerous colossal space stations called "foundations" all across the Solar System. After passing the Space Academy's entrance exams, Shima Katase embarks to the Earth-based foundation Stellvia to fulfill her dreams of seeing the galaxy and to prevent any more interstellar catastrophes from destroying Earth, once and for all.

--- I just watched this again last week, and I still love it. I can't say much about it though that the wikipedia article excerpt doesn't.