Melty Blood: Act Cadenza is a horror-fantasy 2D fighting game developed by Ecole (in conjunction with Soft Circle French-Bread and Type-Moon) and released by Sega for arcades (using Dreamcast-based Sega NAOMI hardware) exclusively in Japan on March 25, 2005.
It is an updated port of the original Melty Blood (and the first released for arcades).
The game was later ported to the PlayStation 2, with a Japanese-exclusive release by Ecole on August 10, 2006. This version includes an optional "Original" mode, adding numerous balance and gameplay changes.
The arcade version received an updated re-release as Melty Blood: Act Cadenza - Ver. B, adding the "Original" mode changes from the PS2 version while adding new changes (such as a new fifth button). This version was later ported to the PC, with a Japanese-exclusive release by Ecole on July 27, 2007.
- Neco-Arc Chaos (variation of Neco-Arc, added in the PS2 and Ver. B versions as a hidden unlockable, has an alternate unplayable giant "Neco Chaos Black G666" version as a hidden boss in the PC version)
- Len (has an unplayable alternate "White" version as a boss character, which was made playable in Ver. B)
- Neco / Neco-Arc (unplayable boss character, made playable as a hidden unlockable in the PS2 version and unlocked from the start in Ver. B)