Looking at D&D, form an "old dudes/dudettes" perspective; what do you like about the older versions, or the versions you started with?
Is it the, implied, setting and world: dwarf/elf/halfling, clerics with blunt maces and cure light wounds, wizards with magic missile and fireball, evil orcs and regenerating trolls, chromatic dragons and level draining undead?
Is it the, implied, game experience; xp mostly from treasure not killing monsters; push your luck delving deeper, combat is deadly but avoidable, less/no skill rolls but describe and think yourself out of trouble and roleplay situations.
Is it the character building experience? Do you roll and interpret your character based on rolls and little, game mechanical, choices and fill out the rest in game through action and description? Or do do you build your character with many meaningful choices and skill attribute/feat combinations that will work at the table?
When you chose to run a D&D game old school, regardless of what edition you chose as basis ( you can 'pimp-up' white box or 'OG-style' 5e, equally valid), what are your 'original D&D experience' elements you try to go back to or introduce?
-deadly-ness for PC's
-push your luck
-gp for xp
-original race/class choices
-old setting like Greyhawk, Dragon Lance mabve Forgotten Realms from the Grey Box Era?
-non-human class level limits and classes limited to certain races
-weapon vs armor type adjustments and weapon speed
-different spell lists for different wizard schools (illusionist, mage, necromancer etc.)
-pantheon including "real world" religion gods like Thor and Athena
-science as magic/post apocalypse remnants, sci-fi influence; our fantasy world is Earth a million years in the future
-stat limits based on gender or race