[UPDATE: Forgot to check the errata. Apparently the numbers have been seriously adjusted downwards and now adjust for stat boosts. Taking this one down for now until I get the new numbers up. I’ll leave it up after the break for the record.]
Last week I looked at core mechanics, this week I get into the mathematical guts of the system. Specifically I’m looking at the target numbers which determine how likely a players are to succeed when they roll the dice. I'm using the numbers from the DnD 4e DMG pg 42 as a guide to exploit their play-testing.
This is not a trivial conversion. D20, since it involves just one die, has a uniform distribution. A player is equally likely to roll a 10 (1/20 chance) or a 20 (1/20 chance). Besm uses two d6 and thus is more likely to roll a total of 7 (6/36 chance) than a 12 (1/36 chance). As a result applying a bonus to a d20 roll gives a consistent return while a bonus to a 2d6 roll varies. The chart. I show my work in a Google Spreadsheet but don't include the base numbers, for that you'll have to buy your own copy.
The d20 scale goes from a bonus of –1 to +9. I’ve factored out level-based bonuses, those get dealt with next week. A negative one bonus, penalty really, means a PC has the minimum allowed value in a stat. A +9 is probably unachievable in most cases unless one has completely optimized the character for that check. The wider range of options makes this easier at higher levels, again I’m ignoring the +level/2 bonus, but it still takes a lot of work.
From this chart, here’s my conclusion.
- Bonuses should range from +0 to +4 over expected values for the tier in question.
- Caps should be 3 above the minimum check for defenses. +4 bonuses should only be achievable via paying a premium for cap breaking. That’s without factoring in tier based bonuses, which means in actual play the numbers will be higher.
- A hard roll will be the minimum bonus +12. (3% to 42% chance)
- A medium roll will be the minimum bonus +10. (17% to 72% chance)
- An easy roll is a tougher call. Both 8 and 9 fit.
- 8 (42% to 92%)
- 9 (29% to 83%)
- This really should be resolved via play-testing, but my instinct says go with 8. Making easy rolls too tough can really make a game frustrating.
- For static targets based on enemy abilities, I’m going with an easy roll and thus 8. So the defensive target would be 8+DCV+defense abilities. As with the easy rolls, some play-testing would help. But I’d rather err on the side of allowing hits as missing is pretty boring.
Next week I’ll get to work on putting these numbers into Benchmarks more useful than the ones Besm 3e provides at the moment.
very nice
good post
Posted by: Jeux | September 29, 2009 at 10:27 AM