ORPS uses 6-sided and and 20-sided dice. Six-sided dice are used most commonly to deal with damage. 20-sided dice are used for skill and default Stat rolls.
20-sided and 20 point capped skills were chosen specifically to avoid 100-sided dice or using a pair of 10-sided dice. If we simply count each point in a skill as 5 points we get a scale that goes up to 100 and could use 100-sided dice instead. This actually helps to lower overall cost of characters by balancing skills versus traits efficiently.
Sometimes you will see something referred to as 1d or 1D and in ORPS this is actually a difference. 1d is 1d6 (and is short hand so we can leave out the 6). 1D is 1d20 (and is short hand so we can leave out the 20). If in doubt assume it is a lowercase d.
Eventually every character faces intense action scenes, high-stress situations, lethal combat, complex investigations, or other scenarios of drama, action, and adventure. To determine the success or failure of the actions they take we do what are called tests. They involve rolling the dice and seeing what chance and skill have to say about their fate.
Three types of Tests exist: Contests between characters, Contests against objects, and a skill roll. We go into more detail on the types in a moment.
When to Make Tests
Ultimately the Game Master decides when characters should make a test and what should be tested. However, as a general rule tests are made when the success or failure could have a significant impact to the story. This includes when two characters (PC or NPC) come into conflict with each other (social, mental, emotional, physical). For example charming the hotel manager into letting your group have the last room in the hotel, when it's already booked. Anything that is routine should not be rolled. Like simply paying for an available room at the hotel from earlier if it had vacancies.
Some things that should require tests:
- Driving while critically injured.
- Chasing someone in a crowded street.
- Dodging gunfire.
- Finding a hidden clue.
Some things which should not normally require a test:
- Driving to work each day.
- Walking behind your mom through a lightly populated store.
- Getting dressed for the day.
- Picking up your keys from the same spot you put them every day.
A Game Master needs to learn to let things ride and when to bring out the dice. That said, a GM can also roll on certain things without telling their players what is going on. So for instance maybe the GM needs to know if the players can spot an enemy sneaking up on them before combat begins. So instead of making the players roll, he can simply make a roll using their skills or stats. Or have his players roll and he does the same for the NPC(s) and only tells them after why they did it, though doing so alerts the players to something being up. For this reason GM's may want to keep the players character sheets on hand.
Contests between characters
Contests between characters typically happen because two characters want different things. It could be a social contest between a merchant and a customer to wiggle out the best deal, or one character trying to hurt the other and the other trying however the can to not be hurt, or any of a hundred different situations where two opposing characters come into conflict.
In these cases each character takes their skill (or relevant Stat) and then rolls a 20-sided die, adding the two together. The highest roll wins. In the case of a tie, the highest die roll wins. If someone rolls a 20 (a 'crtitical' roll) they may either win or reduce the consequences of failure (so a lethal blow, glances off and does half damage for example or a finishing blow that would have taken their head off instead lands elsewhere and they live). If the rarest of all things happen and two characters tie with both sides rolling equally (even critically), then the result is a draw. Game Masters should get creative with draws and critical success on failed rolls as they can become the high points of an adventure.
Contests against Objects
Sometimes a Character is not challenging a specific character, but a device or situation where they must overcome a specific result. A classic example is a character trying to open a lock using the appropriate skill. In this case the player adds their skill or Stat and the result of a 20-sided die together and compares it to a target number from the GM. Whichever result is higher wins as between players, but ties are not an option. Also critical dice rolls in these contests always result in success.
An often overlooked use for this is in cases where a character is challenging the environment. This could be climbing a cliff face, hunting in the forest for dinner, or harvesting materials from a jungle to build a shelter.
Sometimes the only important thing is whether you know or can do something you have skill in and your not contesting anything. This is the only time where the lower the number the better. On a skill roll you want to roll your skill level or less on a 20-sided die. Non-competitive Sports, knowledge skills, and any sort of maintenance or attempt to build something are the most common times to use skill rolls. These can be incredibly important, like winning a weight lifting contest to acquire the information you need… But you are only competing with your self and your own ability.
Defaulting Skills allows you to use a skill you aren't trained in, however their is a stiff penalty for this. Defaulted skills take half the base Stat as their skill level. It is otherwise identical to other rolls whether it is a Contest or Skill Roll. Regardless of how low your Stats are you can never have a defaulted skill below 1.
You may be a big guy with STR 10 and END 10 who doesn't bother to take weight lifting as a skill because you want to default it. Well at half of END 10 your defaulted weight lifting skill is a whopping 5. Another great example is the guy who 'learns' martial arts from watching anime. It should surprise know one when his skill roll is a 1 if he is lucky.
Two or more characters may attempt to work on something together. The one they decide is 'lead' character for this teamwork is the one whose skills act as the base. Take that persons skill and add +1 to it for each assisting character. It's most often done with skill rolls, though some cases exist even for contests. Such as a group of hunters working to capture dinner can use teamwork to provide a bonus to meeting the required target number. A form of this also exists in combat where one team mate near another can help provide a bonus against the enemy.
Bonuses and Penalties
Game Masters should take the situation into account and apply bonuses and penalties to situations. Like climbing up the outside of a moving train should be a little tougher than simply climbing up the outside of a train and the target number should certainly be harder during it. Or a weight lifter who sprained their knee should take a penalty to their skill roll when trying to spot lift some weights. The opposite also holds true. If the character is trying to pick a lock and has a full set of lock smith tools it will be easier than a simple contest would imply.
However both bonuses and penalties should be within reason. No roll should be completely impossible (if it is their is no point in rolling anything), nor should it be to easy (in which case it also should not be rolled). Even if default skill in moving platform combined the player needs to make a skill test with an effective skill level of 1, that is 1 chance in 20. Such miracle rolls can be great for player morale, though failing such rolls can come with big penalties to morale and it's the GM's responsibility to make sure their morale stays high and players have fun.