Whitehack and Scarlet Heroes are two of my absolute favorite D&D old school games. I like the idea of the positive double roll and the freeform character creation and magic system of Whitehack. I appreciate the neat attack roll, the skill system, and the changes to damage rolls for solo playing of Scarlet Heroes.
So here is my monstrous hybrid child of these two interesting games. WH = Whitehack (2nd edition)
SH = Scarlet Heroes

Character Creation

• roll your attributes & assign modifiers according to SH
• classes are from Whitehack: the Deft, the Strong, the Wise
  • the Deft takes the class abilities (armor allowed, weapons allowed, initial HP, HP gained, Attack Bonus, Attack Bonus Gain and Fray Die) from Scarlet Heroes’ Thief
  • the Strong does the same for the SH’s Fighter
  • the Wise does the same for SH’s Magic-User
• the trait system is dropped and simulated with WH’s group system (vocations, affiliations etc.)

Gameplay

• is mostly lifted from Scarlet Heroes: attack roll, Fray Die, Defying Death, healing etc.
• skill rolls: 2d8 + most relevant attribute modifier, if a group is written next to that attributes, you get to make a positive triple roll (roll 3d8, drop lowest) or negative triple roll if the group is invoked negatively (roll 3d8, drop highest)
• check difficulties from SH (p. 17)
• rules for “trained rolls” (WH p. 15) apply
• saving throws: 2d8 + most relevant attribute + character level, if if a group is written next to that attributes, you get to make a positive triple roll (roll 3d8, drop lowest) or negative triple roll if the group is invoked negatively (roll 3d8, drop highest)
• auction rules from WH (p.15) but use SH’s skill checks (see above)
• magic uses WH rules (p. 20) but if a check needs to be made, use the skill system of SH (see above)
• advancement: SH (p. 22)
• multiclassing: SH (p. 23)
• Advancement: XP rules from SH (p.22) but steal slots & groups from WH

I would make a complete game out of this without the need to reference the originals. Whitehack’s mechanics are open content under the OGL but Scarlet Heroes does not use an open license. What a shame.

Links:
Whitehack
Scarlet Heroes (aff)