You may have heard of D100s before, whether it’s rolling on a wild magic table while playing D&D, or in passing when games such as Call of Cthulu or Cyberpunk Red come up in conversation. While the sheer volume of numbers you can roll may sound intimidating, rolling a D100 just involves two ten-sided dice: a D10 and a percentile die (shaped like the image above), both of which are included in any standard rpg dice set.
Rolling a D100:
The percentile dice is rolled first, taking up the 10s place in your roll. The D10 is rolled second, taking up the 1s place. For example, a roll of 60 and 7 results in a D100 roll of 67. Rolling 0 on both dice is how you get 100, and the lowest number you can roll is 01. If that feels a little complicated, they actually do sell 100-sided dice - they look a little like math-themed golf balls. There’s a pretty cool looking one here if you want to see what it looks like.
How does the D100 system work?
D100 systems are based on percentages, which is great for players who want to know exactly what their odds are of succeeding at a given check. As you move along in a game, you add points to various skills. When a challenge comes along, the GM will ask you to roll for that skill. You have to roll the number you have in a skill or lower in order to succeed in your roll.
For example: You have a skill of 35 in mechanics. During the game, there is a problem with your spaceship and the GM asks you to make a mechanics check to fix it. In order to fix the problem with the ship, you must roll a 35 or lower, making your odds of succeeding 35%.
Some games add bonuses to successes if you roll especially low, and penalties to failures if you roll especially high, but these differ from game to game.
Is the D100 system a good fit for you?
With systems such as a D20, the DC (difficulty class) is often not known to the players, and the players are rolling a twenty-sided dice and adding a bonus to it hoping that it will meet whatever that difficulty is. The benefit of this is that tasks can be made harder or easier based on story and what the player is trying to accomplish. This can result in more nail-biting moments for difficult challenges, since the players need to gamble to some degree and wait to see if they guessed the odds correctly.
The dice pool system involves rolling a certain number of dice, with your dice pool increasing the better you are at something. In order to succeed at a task, you need to roll a certain number of, for example, 6s on your D6 pool. The more D6s in your pool, the higher your odds are of getting the number you need. You have some idea of how likely you are to succeed, but the odds aren’t easy to read and right in front of you, like they are for the D100 system.
D100 systems are fantastic for players who want to make calculated risks based on knowing what the odds are to succeed at a given task. Players who prefer to know how hard something is and what their odds of succeeding are before they ask to accomplish a given task may enjoy the D100 system over the D20 system or the dice pool system. Overall, it’s a great system for players who don’t want to wait to know if they’ve succeeded at a given task and who want to know the exact odds of their success in a given task.
Where to find D100 system games?
You can find a great list of games that use the D100 system , and once you’ve spent some time figuring out what game may appeal to you most, you can always find a seat at a table on Start Playing Games.
Maria Oglesby is a professional illustrator and GM who specializes in RP-heavy homebrew 5e campaigns and oneshots. You can play with Maria on StartPlaying.
