Hidden Palace Zone Adventure was a sprite comic by Brandon Vivian, believed to have been started in 2005, sometime before June 26, when the first episode was uploaded to what would be Brandon's first website, Hoaxilery. However, anything more exact is currently impossible to determine, as all the remaining episodes were never uploaded to the website and are now believed to no longer exist. A sequel series was later made, but it didn't last very long.
It is unknown exactly what other characters could've been featured in this series, but they were mostly characters from the Sonic franchise or variations on them.
Only one is known. There may have been 20 or more, as Brandon considered it to be his favorite personal sprite comic and worked on it often.