Summary of the Verse
The Nippon Ichi verse is the collective mass of every game that was developed by Nippon Ichi Software, the reason every game takes place in the same verse is that of how several characters appear in different games (Laharl appearing in Makai Kingdom, Darkdeath Evilman appearing in Disgaea D2 etc). The first game developed by Nippon Ichi Software that became a part of the verse was the three Marl Kingdom games before making games like Phantom Brave, La Pucelle Tactics, the Disgaea series, Makai Kingdom, Soul Nomad and the World Eaters, Z.H.P. Unlosing Ranger Vs Darkdeath Evilman and The Witch and the Hundred Knight 1 & 2. Every game follows a different protagonist in a different part of the verse, like the human world or a different Netherworld. Most of the games developed by Nippon Ichi Software are Strategy JRPGs similar to Fire Emblem or Final Fantasy Tactics, with exceptions like Z.H.P. Unlosing Ranger Vs Darkdeath Evilman which was a Roguelike game, both The Witch and the Hundred Knight 1 & 2 which are action RPGs and Labyrinth of Refrain which is a first-person dungeon crawler.
Power of the Verse
The Nippon Ichi Verse has many powerful fighters in the verse. Low Tier characters (Prinnies and weak humans) are Planet Level, some are Star Level because of their ability to destroy a star, though there are characters from different parts of the Verse that is even weaker than that such as The Witch and the Hundred Knight 1 & 2 and Labyrinth of Refrain which is filled with characters that ranged from Town Level to Country Level.
Mid Tiers are Mult-Solar System Level due to their being fodder demons have been stated to be able to destroy large amounts of stars.
High Tiers are Galaxy Level due to their being characters who can destroy Galaxies but aren't considered strong enough to be a serious threat.
Top Tiers are Universe Level+ due to comparing to Baal who has been stated by the description of one of his attacks that "The Fourth-Dimension is nothing for a Super Overlord".
God Tiers are the eight Multi-Universe Level beings with two of them being Multiversal Level+ and one of them being High Multiverse Level+, Gig, Zenon, Tyrant Valvatorez, Death King Hugo, The One/Valvoga, Evil Mao, the Sacred Tome and the Time Traveller. Gig can destroy multiple universes with his power, Zenon can nullify a powerful attack from Gig, Death King Hugo has several power multipliers with each of his transformations and Tyrant Valvatorez was able to fight and injure him, The One is able to severely weaken Babylon with complete ease Babylon could already fight several powerful Overlords, both Evil Mao and the Sacred Tome can destroy the entire Cosmos which has been stated to contain infinite universes and the Time Traveller has been stated to reset the Cosmos and is infinitely stronger than anyone else in the series. No other character scales to them because of how Gig is far beyond anyone else he has fought, Zenon has never lost a fight in Canon, Death King Hugo has only fought Tyrant Valvatorez at his full power, Tyrant Valvatorez has never lost a fight, The One has never lost a fight, Evil Mao is stated to be stronger than anyone else in the verse and the Sacred Tome can only destroy the Cosmos after the Sacred Tome is destroyed.
In terms of speed feats, the God Tier, Top Tier, High Tier and Mid Tier characters fall into the MFTL+ since they are comparable to characters who can react to and dodge Darkdeath Evilman's Gigantus Ray which travels the radius of the Milky Way Galaxy in one-thirteenth of a second which puts them at being several trillions of times faster than the Speed of Light. However, some of the Low Tier are FTL and the characters who are even weaker typically range around Massively Hypersonic speed.
In terms of Haxs, there are several characters Toon Force users, Poison Manipulators, Time Manipulators, Soul Manipulators, Pocket Dimension Manipulators and several other ways to bypass durability like transforming people into flowers, attacking someone's soul or Reality Warping.
La Pucelle: Tactics
Disgaea 1: Hour of Darkness
Disgaea 2: Cursed Memories
Soul Nomad and the World Eater
Disgaea 3: Absence of Justice
Prinny 1 & 2
Z.H.P Unlosing Ranger VS Darkdeath Evilman
Disgaea 4: A Promise Unforgotten
The Fate Guided Paradox
The Witch and the Hundred Knight
Disgaea D2: A Brighter Darkness
Disgaea 5: Alliance of Vengance
The Witch and the Hundred Knight 2
Labyrinth of Refrain: Coven of Dusk
Human Character Classes
Male Martial Artist
Female Martial Artist
Monster Character Classes
Artifact of Absolute Death