As a roleplaying game, Adreinn is focused on player characters (PCs) interacting with the world and people (non-player characters or ‘NPCs’) described by the Guide. Each player is responsible for one PC, together acting as a Party, while the Guide creates the rest of the world - and the dangers faced by the Party. Coming up with creative solutions using resources at hand to overcome obstacles is the core challenge of the game. To create risk and reward, certain situations will call for dice rolls to determine the outcome. Success or failure are always determined by rolling a 20 sided die and adding some bonus or penalty. These situations include:
-for difficult actions the PCs undertake or to simulate traps or other dangers, the Guide will call for a save. When calling for a save, the Guide will specify a specific ability as described below. To save, the player will roll a 20 sided die and add their ability bonus. If the sum of the roll and bonus are greater than 15, the player passes - if not, they fail.
--In certain certain circumstances, such as players attempting to hide from detection by NPCs, the Guide will call for an opposed roll. Here, the player rolls a 20 sided die, adds specified bonuses, and compares the result to the NPC’s relevant ability static (described below) - if the player’s roll and bonus are greater than the NPC’s static, then the PC triumphs, if not, then the NPC does.
-Finally, in combat with a hostile NPC, the player will roll a 20 sided die and add a specified bonus to see if their attack overcomes the NPC’s armor static. Similarly, when being attacked, the player will roll a 20 sided die and add an armor bonus to see if they successfully defend from an enemy’s attack.
The rolls described above will be modified by bonuses and penalties associated with characters’ ability scores and equipment, but certain environmental factors - high ground, superior planning or coordination - as determined by the Guide may also impose advantage or disadvantage. With advantage a player rolls two 20 sided dice and takes the higher result as their roll, while with disadvantage they must take the lower result of the two dice.
Adreinn uses a system of dice rolls to determine success or failure for actions, damage done by weapons, and other randomized occurrences as determined by the Guide. Those dice will generally be four, six, eight, ten, twelve, twenty, or one hundred (percentile) sided. To make notation easier, going forward these rolls will be presented in the form ‘xdy’ where ‘x’ is the number of dice rolled, and ‘y’ is the number of sides the dice in question have (d stands for ‘dice’). So, if the Guide asked a player to roll 2 dice with 8 sides, that would be noted 2d8. The notation is additive so if the Guide wanted a 4 sided die and an 8 sided die rolled, that would be d4+d8. Bonuses or penalties are presented as constants, e.g. if a player has an attack bonus of 3 then to hit they would roll d20+3.