Things to steal from D&D Next:
• Slower scaling progression
• Resistance reduces damage by half
• Vulnerability takes critical damage
• +1 to a starting ability score for class
Scaling ProgressionWhile Heroes Against Darkness follows D&D's +1 per level progression, D&D Next casts this aside and goes for a completely flat ability score progression and relies on HP increases to simulate the relative power of high and low level combatants.
While I don't think that totally flat progression is desirable (because it reduces the players' ability to feel that their characters are developing in a meaningful way), I do start to worry when characters start to reach +10 (or more) once they're at Level 6. To test out this feeling, I posted a poll on RPG.net, which asked the respondents how fast they thought their character's main ability score bonus should progress.
Here are the results:
+1 per level by tables (e.g. D&D 1-3rd Eds): 10.45%
+1 per level by mechanics (e.g. D&D 4th Ed): 16.42%
+1 per 2 levels (e.g. +1 to primary ability every level): 10.45%
+1 per 4 levels (e.g. +1 to primary ability every second level): 22.39%
+1 per 8 levels (e.g. +1 to primary ability every fourth level): 11.94%
No progression ever: 28.36%
The results here show that about 27% of respondents want some form of +1 per level, and another 28% want no progression ever. Obviously these two groups cannot be reconciled. Based on this statistically insignificant sample, I reckon that the sweet spot is probably somewhere around +1 every third level. This gives players some progression and control over their characters, but it also keeps the escalation of the bonuses (and the scores themselves) under control.
ResistanceMy previous plan for resistances in Heroes Against Darkness was to reduce the damage by an amount that is derived from the monster's ½ Level bonus. D&D Next makes resistance a simple half damage. While the half damage from D&D Next doesn't reflect the power of the monster (a powerful monster can completely negate the damage in Heroes Against Darkness), the simplicity of the maths makes it easier to run.
VulnerabilityAs with the resistances, vulnerabilities in Heroes Against Darkness are currently calculated from the monster's ½ Level bonus, like this:
"Vulnerable Cold: +5 damage per ½ Level of the attacker from cold sources."
This could be simplified by switching to critical damage for vulnerability:
"Vulnerable Cold: Attacks from cold sources deal critical damage."
Ability Score Bonus for ClassThe final immediately worthwhile design element from D&D Next is the association of a character creation ability score bonus with the class, separate from the traditional bonus that is derived from the character's race. This change gives players greater freedom to mix and match classes and races (rather than having to choose the most optimal combination).
Check out the game that the D&D designers should be stealing from:
Heroes Against Darkness - Game Rules.