Designer Diary 2 — All Star Mechanisms

The original Hi/Lo Heroes used Powers to apply a +1 modifier a D6 die roll. It was very simple and the intent was to shift focus from the mechanical to the narrative by keeping the mechanisms simple. (I'm looking at you, Dream Park RPG by Mike Pondsmith — arguably the most influential RPG on my own game design.) This new RPG based on Hi/Lo Heroes will maintain that same spirit of simple design.

All of my latest RPGs use a "house system" that was originally seen in the TTRPG Five By Five. I initially referred to the system as the Five By Five System, but I also briefly called it the DxD System, before finally settling on the High Five System. (High Five fits the system and is a more recognizable term.)

The High Five System is a roll-under resolution system. You simply roll 2d6 and multiply the results on the two dice (instead of adding them) to reach a result that you compare to a target number. 

If you are familiar with D6 dice math, you will realize that this creates a huge and irregular range of results! If that was all there was to it, the system wouldn't work, but there are a few tricks. The first is the "High Five" from which the system gets it's name. It works like this — for each of the two dice that you roll, the highest individual result is 5 — High Five! If you roll a 6, read that as a 0.

When you multiply by zero, all results are zero. To this, I add one final trick — Doubles always succeed. Now the High Five roll that involves rolling the 2d6 and multiplying will produce a success for a character with a Target Number of 2 fifty percent of the time. Also, all the numbers left have an equal 1 in 18 chance of being rolled. No bell curve. Very close to the probability on a D20. It's the perfect roll under system and it uses the D6, which has always been my preference.

The target number array is: 0, 2, 3, 4, 5, 6, 8, 10, 12, 15 and 20. Twenty is a guaranteed success. It is the highest value that you can roll. (All Doubles are an automatic success so 25 (5x5) doesn't appear, 6 is 0 so 24 and 30 don't appear. After 0 (which has about a 44.5% chance of success) every number adds about a 5.5% chance to your odds. (As mentioned, 2 is 50%, 3 is about 55.5%, etc.)

Zero is where the magic happens!

You can do this with a d20, yes. But I love the idea of 0 being my baseline. No math. No remembering. If something doesn't exist on your character sheet, then its value is zero. Easy peasy! This is the whole premise of the Five By Five RPG. You only list your exceptions and everything else is an assumed 0. It's intuitive and it uses the D6 which I prefer.

Original versions of the game system used the full array of 0, 2, 3, 4, 5, 6, 8, 10, 12, 15 and 20. But can you see the problem? The array was irregular and difficult to modify on the fly with things like bonuses and penalties. I decided to smooth things out. I made all skill level values an even number from 2 to 10. I left the ends open so the GM could apply a -2 penalty to the 2 and hit zero, or a +2 bonus to the 10 and hit 12. We lose 15 and 20, but 20 was 100% so was never viable as a skill level and I was okay with losing that last 5.5% and topping my highest probability of success at around 90%. 

Bonus and penalty mods are applied in increments of + or - 2. GMs can even apply a -2 penalty to a non-skill of 0 and reach -2 (which can still succeed if the player rolls doubles.) The only slight glitch here is that jumps from 2 to 4 and from 4 to 6 skip over a number in the array and are therefore 11% changes, not 5.5% changes.

In the end, I kept the 2 point incremental range. I am okay with the greater jump at lower values. Isn't that how people learn? The more you know about a topic the closer you come to a plateau and increases in ability slow down? My array is reflecting that tendency completely by accident.

What does this have to do with Stars? 

Every number in the established target number array is an even number. The core values for ability scores are 2, 4, 6, 8 and 10. It occurred to me that these five levels of value could be stars from ★ to ★★★★★. People understand a five star rating. Adding and subtracting stars is easy. To find a target number just total all the stars and multiply by 2. That's the system. A Hero with a ★ Ability has a 50% chance of success. With ★★★★★ it increases to an 83% chance. It's a quick easy system with a rating method that people recognize.

Star Ratings are now the new way to define abilities in the High Five System. Star Ratings are familiar and intuitive. Stars cannot be applied directly to dice rolls, so the GM or Player will never try to apply modifiers (which are now expressed in stars) to the dice. They must apply modifiers to abilities. (This has been a point of confusion on occasion in the past.) Plus, dealing with values mostly falling between 1 and 5 will keep all of the math super simple.

Hope all this game math wasn't too boring!

Regards,

Jeff