O5R
To get a OSR or B/X or BECMI(Cyclopedia) feel consider using the following traditions and 5e variant rules.
Character Creation
- roll 3d6InOrder for ability score
- select only from races and classes in the free D&D 5e Basic Rules
- Remove skills from the game and consider using the DMG variant rule that grants characters some proficient rolls based on Class, Background, or Personality Traits
- every adventurer is given the standard adventuring gear pack
- may want to toss in some pitons and a 10ft pole
Gameplay
- consider removing or limiting the use of cantrips (Spell casting modifier + Proficiency uses per day)
- drive for the general use of abilities and have players request use of a proficiency
- Use DMG Variant rules for Resting that takes a Long Rest up to an entire week.
- Use the DMG Morale option (DC10 Wis save) for monsters when surprised, forces half defeated, or obviously defeated
- Grant XP for each GP returned to safety
I plan to try some of these out and generate a more firm listing of tried practices.