The characters go hex to hex catching the Pokemon-like monsters on the island; the Zodiac wizards are the Gym Leaders to be defeated; the clerics are helpful trainers; the statues are ways to access the Pokedex.
Wizard Fighter II: Super Turbo
The wizards on the island have all come to the island to do battle with each other, Magic: the Gathering-style, but the rules of engagement state that they cannot leave their chosen territory. This means that they compete with each other by vying for agents to sabotage and attack the others. That’s where the characters come in: who will they ally themselves with, and what reward is offered? Will they betray their patron if a better offer comes along, or do they fight for some higher ideal?
Weird Game Hunt
The characters are big game hunters exploring an uncivilized island, looking to bag some freakish trophies to mount in the ancestral manor. This probably isn't the most politically-correct idea in our post-Cecil moment. Mix in some of H. Rider Haggard's She for kicks.
The wizards have all come to the island to perform a great magical working that requires them to complete a vast ritual in concert with each other ; their positions on the island all relate to a web of ley lines. However, there is some Ancient Evil that wants to prevent the beneficent ritual from happening. That’s where the characters come in: how will they safeguard all of those wizards from attack by the minions of the Ancient Evil?
Missionaries in a Pagan Land
The clerics on the island are all missionaries who are bringing the light of the One True Religion to the pagan isle. Cut off from the homeland, the clerics are counting on the characters to deliver much-needed supplies (bibles, food, weapons--maybe not in that order) to counter the pernicious influence of the isle's powerful pagan leaders (the Zodiac wizards, naturally). The statues are pagan idols (or perhaps the earthly manifestation of the pagan gods themselves) to be toppled and destroyed. Win hearts and minds, or bring religion with fire and sword--your choice!