Alternity Design Blog #2: The Core Mechanic

alternitylogowhiteonblackLet’s face it—any discussion of the 1996 Alternity game begins with the distinctive core mechanic of the game, as the original game had a novel take that used a d20 and one or more other dice for resolution, with the possibilities of different levels of success based on the result. In this week’s Design Blog, Rich takes us through our process as we evaluate the core mechanics for Alternity 2017. 

The Starting Point

For those of you not familiar with the original Alternity system, here’s a brief description: Every major test or task your character attempts, from shooting a bad guy to fixing a story-critical piece of gear or influencing a suspicious NPC, can be resolved by rolling a d20 and trying to get under your skill score. So if you have a Strength of 12 and 3 ranks of Bludgeoning weapons, you need to roll 15 or less to succeed at the test of whacking a street thug with a baseball bat.

This basic resolution mechanic was refined by adding or subtracting a situation die to reflect various complications or advantages. The thug is distracted by playing Pokemon Go? Awesome, he doesn’t see you coming, so you take a bonus of –1 die step. Now you’re trying to roll 15 or less on a d20–d4. The alleyway is filled with thick smoke and you can barely see the thug? Hmm, that might be a +2 die step complication, changing the test roll back to d20+d4. Oh, and you’re severely drunk, and you’re on fire. That might be another 2 die steps of complication, so now you’re rolling d20+d8 and trying to get 15 or under. The GM could easily handle different situations by scaling the situation die up or down on the fly.

Design Directions

In our Alternity, we’d like to retain the two-die concept, and hang onto the polyhedrals and the idea of modifying a skill check by sliding up and down the die scale. But we’d also like to update the mechanic by flipping it to a roll-high system. It simplifies some concepts, like having “bonuses” add and “penalties” subtract, plus people like looking for high numbers on their attack rolls, and it will also make Alternity an easier conversion for other systems. We considered two basic approaches to updating the core mechanic: the Skill Score method and the d20 System method.

D20 System Method: In this approach, we would use a core mechanic much like that in any 3e-era d20 game: the target of your action provides a target number (Armor Class or Difficulty Class); you roll a d20, add your abilty mod and skill ranks, and try to beat that number. To “Alternity it up” we would use a polyhedral situation die in place of most static modifiers—so, shooting at a guy in cover might be a -2 die step penalty instead of a –4 penalty. We might even go so far as to remove skill ranks altogether, and use your skill ranks as a natural die step modifier (so gaining skill “ranks” might instead give you a default 1-, 2-, 3-, or 4-step situation die on your skill).

Skill Score Method: This method is a more direct “flip” of the old Alternity mechanics. You figure your skill score for various actions or talents by subtracting your ability mod and your skill ranks from, say, 15. So, if you’ve got a Strength bonus of 2 and you have 5 ranks in Brawling, you have a Brawl skill score of (15–2–5) 8. When you punch somebody, you’ll roll a d20 and try to get an 8 or higher. As in the original Alternity game or in the d20 System method described above, we add a polyhedral “situation die” to represent tests that are easier or harder for the active character. Conditions that favor you add a die to your roll, and conditions that work against you subtract a die from your roll—punching a guy who doesn’t see it coming might mean rolling d20 + d6 and trying to get your 8 or higher.

Comparing Methods

We initially considered the d20 system method because it’s so commonly used in current RPGs, and it’s a system we are very familiar with from a design perspective. But we found that the Skill Score method offers some subtle advantages. It actually moves faster than a typical d20 system because you’re not constantly checking with the GM to find out if your total was high enough to succeed. (Ever play the “What’s the monster’s AC” mini-game at your D&D table?) The Skill Score test is a simple comparison; did my roll reach my target number or not? And it’s a two-step operation (d20 plus or minus a die) instead of a three-step operation (d20 plus my modifier plus or minus a die). While it’s a little counterintuitive to get better by decreasing your skill score, that math happens between sessions, so it doesn’t hamper actual play.

So, for our initial development, we’re going to test the heck out of the Skill Score method. We think it’s faster and better than the d20 approach, at least for a modern/SF action-oriented RPG. In addition, it’s a little more faithful to the original game. You’re just trying to roll over your target number instead of under it. And if it turns out that our playtesting shows us otherwise, we can very comfortably fall back on a more conventional d20-style approach, because we know plenty about putting those systems together.

Success Grades

One other element of the original Alternity mechanic is that you can score better-than-ordinary success on an attack or check by making an especially good roll. It’s important for us to retain that part of the core mechanic in Alternity 2017. There is a super-easy way to do this in the Skill Score method: set a margin above a typical success for each additional level of success. For example, as a starting point we could say that if you beat your target by 5, you get a Good success; if you beat your target by 10, you get an Amazing success. So if you punch that guy who doesn’t see you and get a 17 on your d20 and 4 on your d6, you total 21. Your Skill Score is 8, so an Amazing success is anything that totals 18 or better—you really clock the bad guy!

bridge ruins finalGetting the core resolution mechanic was our first step in the system redesign. From there, we can create character abilities, classes, and gear. We can look as subsystems like skills and durability/damage. We can build challenges and foes. But more importantly, we can sit at the table with makeshift characters and get a feel for how the new Alternity plays, now that we’re rolling!