I don't know much about the game, but I believe 5 Torches Deep was marketed as a sort of OSR-ified 5e, as well.
The free preview for Five Torches Deep (
https://www.drivethrurpg.com/product/264584/Five-Torches-Deep) has on page 2 their approach to mixing OSR and 5e.
The whole ruleset is only 49 pages long. Summarising:
Characters - only go up to level 9, four races, four classes, 3 archetypes each, archetypes gain one feature from a list of 7 at levels 3 and 7.
Damage - dropping to 0 hp is likely to inflict permanent injuries.
Spellcasting - Has cantrips, but none are attacks; each class only has 5 spells per level, and levelled spells require a casting roll. Weaker than 5e.
I got it in a package with Highfane Deep, which is a somewhat longer setting cookbook for 5TD *
- three replacement races
- a "prestige class" for each of the four base classes; the two that are spellcasting have 3 additional spells per level
- a few alternate archetype features for characters from the region
* "cookbook": it's a bunch of themes and ideas and random tables to build a setting with; there's not an actual map or concrete details. I actually had it open today because I do think the mountaineering rules can probably be yoinked my a regular 5e game if it runs tonight.