Is it house-ruled D&D or a new game?

A current discussion over the odd74 forum deals with the question of what constitutes a new game and not a house-ruled D&D. I offered the following hypothetical games in whose case it may be decided whether they are D&D or something else. I firmly believe that the answers could help us establish a simple baseline to what D&D is and what it is not.

• No. 1. Exactly like B/X but with a spell point system (but the point costs can be reverse-engineered into the original spell levels); thus, rules for spell point recovery, spell point-based magic item creation.
• No. 2. Exactly like No. 1. but with spell schools and specialised wizards, for whom the spell point costs are also varied by schools and not only the original spell levels.
• No. 3. Exactly like No. 1. but the spell point costs are not related to the original spell levels anymore.
• No. 4. Exactly like B/X but no Hit Dice; instead, a flat number of HP is gained upon each level, and monsters' have a fixed number of HP, too.
• No. 5. Exactly like B/X but no character classes; characters are built from powers (which resemble cast abilities: attack bonus, saving throw bonuses, turning, casting, thief skill, etc.).
• No. 6. Exactly like B/X but uses d100 instead of d20. The probabilities are the same, though, only the die size is changed.
• No. 7. Exactly like B/X but uses 3d6 instead of d20. The probabilities are sometimes drastically changed because the bonuses and penalties are not adjusted at all, only the die rolling mechanics.
• No. 8. Exactly like B/X but uses a single die roll to determine the outcome of battle. Other sub-systems (spell casting, non-combat spells, thif skills, movement, advancement, etc.) are untouched.
• No. 9. Exactly like B/X but character advancement is based on (a) "role-playing" (acting like your character, doing a voice, etc.), (b) clever solutions, and (c) witty remarks in-character that bring laughter to the table.
• No. 10. Exactly like BX but adjusted to a 1on1 setup with no henchmen or followers. A single hero versus the world.