Grainger
Explorer
I'd more likely to define the "D&D experience" not with reference to the rule set but with reference to table expectation. Even here there is an awful lot of drift especially after 1e, but I'd say a D&D game consists of:
- Indifferent universe. The universe is neither helpful nor malignant. It just is. How the PCs navigate the challenges and opportunities matters. Success or failure is rarely certain and almost never due to who the PCs are, but to what they can achieve.
- "Zero to hero" play. Starting play the PCs are generally weak, but if they are successful they can become among the strongest ever seen.
- Archetypes are common. Every PC incorporates one and mechanical variances are minimal. Making the character yours comes through personality and in-game experiences.
- Treasure matters. Much of your ability can come from what you can wrest from the world.
Treasure doesn't matter much in my campaign, and I never thought of my game as being "not D&D" (for what it's worth, I've been running campaigns since the mid 80s). These days, I wish my players would try something other than D&D, and I'm going to stretch the system as far as their tolerance will bear, but that's in the future - to date, my campaign has in no way been "not D&D", at least in my view.