You are the last descendant of the Guardians of the Gates. Zeus, creator and ruler of the Guardians of the Gates, raises you from your grave! To this end you must go forth and defeat a new, unknown evil that has been ravaging various worlds to collect the Keys and essences of each one. Gates are inter-dimensional and interplanetary portals that, after being opened with the proper series of Keys, allow anyone to travel to any of the infinite planes of existence.

A Great Evil (The Dark Reaper) has hunted the Guardians and stolen their Keys and Spirits. Spirits contain the secrets of life on various worlds. Using the Gates, The Dark Reaper is building armies and hiding them in many different worlds. It is up to you to defeat these armies, recapture the Keys and Spirits, and defeat The Dark Reaper. As a descendant of the Guardians, you have the ability to imbue yourself with an essence specific to each 'Plane'. These essences are called "Spirits."

Some Planes have multiple essences, and some essences allow for any shape if you have the proper power and can find where to tap into it. By traveling to these other realms and recapturing the lost Altered Beast Spirits and Keys, you will gain power, hopefully making it possible to emerge victorious against something dangerous enough to have defeated the other Guardians in the first place. Since you are the last Guardian, you will become the sole protector of the Keys once you have regained them.


  • Based on the arcade hit
  • Morph into one of four powerful beasts
  • Awesome side-scrolling fighting action
  • Great graphics and sound
  • Brilliant one or two player action

This game is also known as Juuouki in Japan.

Forum Posts


Sega Genesis Classics Series 1 released for PC

Play classic Sega games on your computer

Jun 01, 2010, by Dany Argueta | 7 comments
Sega fires up PSN & Virtual Console Christmas sale

40 percent off digital download games and DLC, including Valkyria Chronicles missions

Dec 22, 2009, by Leo Chan | 0 comments

Latest Activity

May 13, 14 7:41am

Most gamers know what Altered Beast is, but how many of them know of an NES port? Probably a few...

Dec 16, 11 8:37am
Was on my last bit of health on the final boss, had no lives left, then dashed into the rhino. It was pure luck. AlteredBeast
Monterey Jack
Sep 19, 11 8:36am

NOTE: This review is based off of what I played on Sonic's Ultimate Genesis...

Dec 30, 10 6:20am
added 5 new screenshots
Jun 17, 10 11:42pm
Feb 5, 10 11:22pm
this game is beastly nuf said AlteredBeast
Aug 28, 09 2:02am
arise from your grave xD it's a nice game to play with two people. AlteredBeast
May 11, 09 7:11pm
added 8 new screenshots
Mar 18, 09 9:22am

Altered Beast for the Sega Genesis was best known not only as a decent...

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Release Dates
  • North America:
    • Dec 16, 2010 (iPhone)
    • Jun 10, 2009 (XBOX360)
    • Nov 19, 2006 (Wii)
    • Dec 31, 2001 (c64)
    • Dec 28, 1989 (SEGAMS)
    • Aug 14, 1989 (GENESIS)
  • Japan:
    • Dec 2, 2006 (Wii)
    • Jul 20, 1990 (NES)
    • Sep 29, 1989 (tg16)
    • Nov 27, 1988 (GENESIS)
  • Europe:
    • Dec 8, 2006 (Wii)
    • Q4 1989 (c64)
Collections Summary
54 own | 0 want | 11 completed