From the website. "www.pentologygames.com"
Pentology is an adventure card game. While the core mechanics remain constant, the cards are designed for use in any number of different games. It is most comparable to a standard fifty-two card deck of playing cards. Although it does not have suits and numbers, jacks or queens, Pentology does allow mathematically sound strategy; group, team or solo play; simplicity or complexity; all with the same deck of cards.
Pentology further provides players with a backdrop fantasy theme for every game. With Pentology cards, solitaire games become a mission of saving your allies and defeating your nemesis; poker style games suggest the fun of defining the characteristics of your own hero, and then pitting her strengths against your opponent's; and blackjack feels like a quick skirmish.
Standard playing cards have long been popular because of the vast number of games that can be played with a single deck. Pentology cards boast that same value. Each deck includes a rulebook with rules for five different games, and as creative enthusiasts come up with new game rules and post them on the forum, the list of available games will grow.
With the support of online community, players can continually find new games, contribute their own ideas, and vote on which games to standardize.