D&D Reduced to Just Three Mechanics

How weird does D&D 5E get if you strip it down to just three mechanics? 

I am talking about a Lasers and Feelings-style one-page RPG, with just three mechanics, all drawn from my grand list of D&D 5E mechanics. I rolled randomly, and these were my results.

• 28 Feats and Boons
• 15 Conditions and Exhaustion
• 49 Proficiencies (Armor, Tool, Weapon, Skill, Saving Throw)

OK, not as weird as I feared.

Proficiencies can be gained through advancement, but most of them are things characters get at character creation. I think of this as a loadout mechanic. 

Conditions and exhaustion are complications and drawbacks. Perhaps in this game there is no HP, wounds, or death system; characters simply acquire conditions until they are fully out of danger, or until those conditions pile up such that they are incapacitated and out of action.

Feats and boons are methods of advancement. Clearly we’re dealing with a classless system. Rather than more HP or spell slots, feats and boons tie into the proficiencies, improving or building upon them in some way.

This is a rogue-like dungeon-delver. You are a dungeon raid manager, who assembles teams of junior adventurers to raid a dungeon. You start with a pool of meeple adventurers. You get a bunch of hirelings with one random proficiency, a handful of henchmen with two random proficiencies, and a few heroes with three random proficiencies. 

You assess the dangers of the next dungeon in some structured fashion (maybe a "20 questions" game). You then pick a team based on the proficiencies you think will be most useful in meeting that challenge. This game would require some testing to ensure the player can anticipate what tools are right for the job. Proficiency in constitution saving throws is clear for tackling a dungeon full of monsters that cause the poisoned condition. Other proficiencies are less obvious in their application. 

The more accurate your assessments, the more successful your delve is, and the more feats and boons the adventurers earn after they come back. If your guesses were off the mark, they come back with various conditions or levels of exhaustion (if they come back at all). If this happens, they’re unavailable for one or more subsequent dungeon raids, and your pool of options is smaller for those explorations.