Outside the visual upgrade,
Disgaea 4: A Promise Unforgotten is pretty much the same game as past releases. Although a few new mechanics have been added or tweaked, the core strategic gameplay is largely untouched.
For those new to the series, here's what to expect. The core gameplay is based around marching units around a grid-based map with the goal of wiping out the other group. The idea is simple, but loads of strategic goodies are tossed in, making it one of the most insanely deep - and complicated - SRPGs on the market. It is also one of the best. In addition to moving troops during battle, you have to consider their placement on colored panels called "Geo-Panels," which grant different statistical adjustments (both good and bad) to whoever is standing on them. You also have to consider troop placement, since nearby units can team up, leading to multiple attacks per turn.
Disgaea games are known for their off-kilter stories, and Disgaea 4 is no different. You play as Valvatorez, a "reformed vampire" (he refuses to drink blood) who gives up his position of Netherworld Tyrant to work as a drill sergeant in a Prinny prison. For the newcomers, Prinnies are demon penguins birthed from the souls of corrupt humans. Think of them as a living purgatory, but armed with knives and with a propensity for exploding when hit.
Prinnies are the absolute bottom rung in Netherworld society, yet Valvatorez has developed a bit of a bond with his trainees. When a group goes missing just before graduation, he decides to set out and find them. Eventually, Valvatorez's search develops into a quest to rid the Netherworld of corruption, putting him at the front of a coup against the President. As with other games, the story is packed with twists and turns, along with a cast of odd, yet amusing characters. The game is also genuinely funny. Although it doesn't hit the same satirical hot spot as the original, Disgaea 4 is incredibly smart and funny.
What happens on the battlefield is only a small part of the entire experience. You'll spend just as much time off the field, navigating through various side-options, like the monster builder and new Cam-pain Headquarters. Building on the game's political theme, the Cam-pain Headquarters shows an overview of your conquered territories. Here you place facilities on parts of the map, applying bonuses and other boosts based on where things are placed. It's tempting to randomly place structures, but bonuses are incredibly important later in the game.
Unfortunately, the Dark Assembly, a voting sequence where you need to "convince" Senators to help you get things done, is still a major play element. Now, however, you can stack the odds in your favor by placing your troops in positions of power through your Cabinet. Depending on where you place characters, you can unlock additional abilities and features. Again, you'll spend just as much time making decisions off the field, as you will on.
Another noteworthy addition is the network features. Although you can't battle other player's battles, you can jump into other player's games similar to Demon's Souls. You can send a character to infiltrate another player's Dark Assembly, or create a roaming band of enemies to disrupt players in the Item World.