The classic Call of Cthulhu game, by Chaosium,is renowned as a game of cerebral stimulation and intensive, chilling scenarios set in a world like our own, inspired by the writings of HP Lovecraft and others. The D20 system is the outgrowth of the latest of the editions of the Advanced Dungeons and Dragons game, by WotC, emphasising heroic daring and high magic. When it was announced that the two games would be blended together, many believed it would fail. Surely two such disparate styles of play could never be integrated? Yet those fears have proved unfounded. The D20 adaptation of Call of Cthulhu serves as an example of just how versatile the D20 system can be, with various "tweaks", such as deadlier damage, sanity loss and magic dangerous to both self and soul highlighting how the existing mechanics can be implemented to make a grittier, more realistic game. Character creation is handled in a more flexible manner, allowing customisation of strengths, weaknesses and abilities of the character desired for maximum enjoyment. Detail is given in the book to the most important aspects of Lovecraftian horror, including exhaustive sanity rules, an over-view of the Cthulhu Mythos, and a "monster manual" of Mythos horrors. The artwork is of a high standard, as usual for A WoTC product. And for more traditional D20 players, there is an appendix at the back for hybridising the two games (Call of Cthulhu and Dungeons and Dragons). Of course, the book does have its flaws. The attention given to both monsters and firearms (in the equipment chapter) unwittingly encourages a "kill the beasty" approach to the game which is not really what Cthulhu should be played for (though this does have its charms), and a few of the rules favour certain choices, such as the defensive vs. offensive character option, which yields more immediate benefits to the defensive, without even the "balance" factor of a gain for the offensive choice later (whilst an offense character will take over in the attack scheme, which any character will be unlikely to see, nor is this a recoup against the defense's superior save). A final fault was with the layout, which is arranged in a strange "diagonal" fashion, though I persoanally found this enforced the madness theme of the game to some extent. These gripes are minor, of course, with the book being of overall high quality with a solid grounding of rules and setting details firm enough to intrigue, but not so clear that there is no mystery. I would highly recommend this volume to any fan of roelplaying, whether WotC's D20, Chaosium's Basic Role Play or other sundry system.