Popful Mail is a video game created by Falcom which combines platform action with RPG elements and a delightful fantasy plot, originally created for NEC's PC-88 in 1991, but ported to several systems during the early 90's. This site deals mainly with the Sega CD version, which is the most famous and generally thought to be the best.
Popful Mail has seen many different versions on different platforms. It was originally created by Falcom, a Japanese company famous for series such as Ys and Xanadu, released for the NEC PC-88 in 1991, and PC-98 in 1992. This game was ported by NEC to its more advanced PC Engine Super CD console (known in the West as TuboGrafx or Turbo Duo), with better graphics and sound and additional voice acting.
Around the same time Sega ported the game to its Sega Mega CD system (known as Sega CD in America). Like the PC Engine version, this as well featured voice acting and even better graphics. The gameplay, however, was radically changed. The NEC versions featured gameplay reminiscent of Falcom's Ys series, where you attacked by running into enemies. The Sega version featured more traditional platformer gameplay, where you attack by slashing or shooting with various weapons. This version was brought to America by Working Designs, and is the only English language version available. Also in 1994, Falcom ported the game to Nintendo's Super Famicom (that is, the Japanese SNES). The gameplay, like in the Sega version, was on traditional platformer lines, although the stages were entirely redesigned.
In Japan, the games also spawned a series of drama CD's, a very popular format there.
You can read more about the different versions here.
At the beginning of the game, Popful Mail, an elf bounty hunter, has just been defeated by the notorious villain Nuts Cracker. She hasn't learned her lesson, though, and immediately sets out after an even bigger bounty for a renegade magician, Muttonhead. On the way she meets Tatto, Muttonhead's former student, who is also searching for his mentor (out of concern rather than greed). Little do they know that Muttonhead is only a pawn being used by a far greater evil waiting to return to the world...
Popful Mail is most commonly classified as action/RPG. It does indeed contain many RPG elements, such as buying better equipment and healing items, talking to people in villages and a general emphasis on plot and dialogue. However, the gameplay on average is pretty standard platformer material, and the game also lacks some common RPG elements, like gaining experience. The only way to improve your stats is to get a better weapon or armour, and there's not a huge amount of them to collect... It is, then, a matter of taste whether you wish to call it simply a platformer or an action/RPG game. I think it's somewhere in between.
Director: Victor Ireland
Assistant director: Dean Williams
English translation: Akiko Skjellerup, Horkom International, Victor Ireland, Dean Williams
Sound engineers: Bill Staeck, Don Shirley
Additional music: Bill King
Reprogramming: Shigeo Koyama
Popful Mail: Melissa Gulden
Gaw: Blake Dorsey
Tatto: Shaun Watkins
Muttonhead: Keith Lack
Nuts Cracker: Blake Dorsey
Slick: Ashley Angel
Glug: Nance Davis
Sven T. Uncommon: Matt Atwood
Venuncio: Greg Soriano
Mumbles: John Truitt
Wriph: Marilyn Weeks
Wraph: Katie Staeck
Lipps: Mike E. Miller
Kazyr: T. Owen Smith
Song performed by: Jennifer Stigile
I may consider writing my own walkthrough some day, but for now you can use the one by Lady Raven, which you can find at GameFAQs.com, here.