Structure: Shadows of Malice is a cooperative game -- either the players win together by thwarting the Shadows or the Shadows defeat the players.

Setup: players choose 1-4 terrain maps for the game. If they choose X-many maps, there will be X light wells and 2X dark wells in the game. These are randomized and hidden in the strongholds on the X-many maps (so all light wells could be on the same map).

Player objective: go to the strongholds, defeat the stronghold guardians, and reveal wells they guard. To win, the players must reveal all X-many light wells before a Shadow can reveal any one light well.

Playing the game: The game proceeds in pairs of turns: the players' turn followed by the Shadows' turn. On the players' turn, each player may have his game avatar either:

1. Rest and recover
2. Perform a special action on a revealed light well
3. Move and/or engage the service of a city or mystic
4. Move and/or engage in combat with a creature

A player's avatar may encounter a twist of Fate on their turn, based on whether or not they are required to draw a Fate card.  Players engage and defeat creatures in lairs to acquire treasure items and soulshards. Players' avatars all have the same "stats" (e.g., life, movement, etc.) but each possesses a unique special ability called a "mastery" (e.g., the ability to redo die rolls, a better chance to hit an opponent). Players' avatars do not level up. Instead, treasure items and potions are used to buff up the players' avatars so they can grow powerful enough to take out a stronghold guardian and reveal it's well. Soulshards are crystallized life essences harvested from defeated creatures that the players collect and can invoke to activate mastery abilities or invoke to increase or decrease their die rolls or the die rolls of other avatars. Treasure items, potions, and soulshards may be freely traded among avatars at any time except during combat. Cards are used for treasure items and potions in the game; acrylic gems are used for soulshards.

Creatures are always encountered individually and are randomly created when encountered (because the Shadow Lord's evil mutates the natural denizens of the world in random ways). Players roll dice for each encounter to determine a creature's type (e.g., mammal, reptile), it's power level, and whether it has any special abilities (e.g., poison, death gaze). Cards are used for creature abilities. Treasure comes in the form of items and potions, and is awarded based on where the creature was encountered. Soulshards are awarded based on the creature's power level and abilities.

Combat is played out by rolling dice and modifying the rolls by creature power level and abilities, and avatar buffs and bonuses. Creatures and avatars sustain wounds and/or drains from combat. If they lose all their life to wounds and/or drains they die. Dead avatars reform new bodies and re-enter play. Dead creatures stay dead.

On the Shadows turn, Shadows in the Shadow Realm spawn and grow stronger and try to enter the game maps, while Shadows that managed to enter the game maps seek to defeat a stronghold guardian and reveal a light well.

If a Shadow defeats a stronghold guardian and reveals a dark well it will proceed to another stronghold in search of a light well. If a Shadow defeats a stronghold guardian and reveals a light well, it will render the well dark and transform into the Shadow Lord Xulthûl. The Shadow Lord will seek to snuff out all light wells. The players may still win the game by defeating the Shadow Lord before it extinguishes all the light wells. If the Shadow Lord extinguishes all the light wells, it conquers the world and the players lose.

Each revealed dark well increases the chance that an encountered creature will have abilities. Each revealed light well grants a random lasting buff to each player’s avatar.