It looks like an old-skool JRPG, but plays like a puzzle/adventure game. It's fun and frustrating, but worth a play.
The game tells the story of a group of school children and their teacher taking part in what they think is a silly occult "game" or mock ritual, only to discover it's essentially a trap that whisks them away into an alternate dimension. This dimension is occupied by a myriad of ghosts that have been involved in a series of horrific crimes and tragic events, and the characters must work their way back to the real world. They must avoid going crazy, being possessed by evil spirits, and avoiding being killed by each other or other evil beings.
The story and characters are what shine in this game: it's a compelling, sometimes tragic, sometimes moving story of these friends. They are forced to evaluate their own lives, make moral choices, and confront internal and external "demons".
The graphics are 2d top-down, low-res sprites with occasional detailed manga drawings to show character portraits or individual moments in the game. The manga drawings are very well done, and actually the 2d sprites look great and are intentionally, nostalgically crude, but still colorful and detailed. Details in the game are told via voice-overs/text, sometimes with just a black screen. While that sounds like a cop-out, the descriptions are extremely well done, detailed, and often gruesome.
The sound in the game is great, from excellent Japanese voice-overs (with English subtitling), to good use of sound effects, to a varied and very good musical score.
The game clocks in at about 8-12 hours, depending on your luck. This is a game where it's easy to make some wrong choices that lead to a "Wrong End", and I ultimately did use a walk-through on the final chapter to succeed, because particularly in the last chapter you can make choices that prevent a good ending, but you may not know for 30 minutes of play that it was a bad choice.
That's really my only complaint -- the game is very linear, and not really "hard". It's more of an interactive story with some light puzzle elements.
But again, for fans of Japanese horror, or horror stories in general, Corpse Party is well done and very immersive.