1. Character creation has some form of in-game consequences
2. Statistics which define character(s) abilities are subject to change throughout the game
3. Character(s) have skills or abilities which may improve or be altered over the course of gameplay
4. Character(s) accrue experience which can be spent or result in gaining levels or abilities
5. Character(s) accumulate items in some form of inventory, which the player can actively use (equip, sell, destroy, trade, etc.), which enhance or otherwise alter gameplay
6. Character(s) accumulate currency which may be spent to enhance the character(s) in some way (items, guild membership, training, etc.)
7. Character(s) gain levels throughout the game which result in some form of mechanical change (not just a change in character title, or description)
8. Character(s) are able to explore over terrain, water, space, etc. ('explore' refers to free movement of main character(s))
9. The game has some form of puzzle solving, which is resolved through combat, problem resolution, or some choice made by the player
10. A choice made by the player alters the narrative, or some other significant part of the game (an item is found or lost, stats or skills are gained or lost, different ending, etc.)
11. Character(s) interact with NPCs in some form of dialogue which have in-game consequences depending on what the character(s) say.
12. Optional quests (defined here as some kind of task made available after the game has started, and which can be resolved by the player before the game ends, but is not required to complete the game) are available.
These are NOT definition for roleplaying game in the context of computer/console rpg. For a list of number acceptable elements that a game must have before it can be consider a computer RPG,
please check here.
1. Character creation does not have to exist in an RPG. You can still play the predesigned role, even affect it.
2. Statistics or attributes do not have to change at all!
3. Check, it is correct.
4. Experience is all fine. Morrowind sets the other example, that skills advance through usage.
5. I can imagine an RPG without an inventory system although... Check, it is correct.
6. A currency is part of the setting, unrequired.
7. Again, Morrowind proves the point wrong.
8. Exploration! Check, it is correct. Although should be simplified to actions/deeds.
9. Riddles vary. The ones in the story don't have to be. The ones in tactical combat neither.
10. Your choices alter the story, absolutely. Check, it is correct.
11. Once more, yes. Check, it is correct.
12. Side quests do not have to be.
To summarise, four agreements. Which leads to me thinking this. Story, Deeds, Consequences. These are the marks of an RPG according to me after reading these 12 points. Another good point is that a Role-Playing Game is simply a port of a Pen and Paper. Better to build a Pen and Paper and create a video game out of it rather than create a video game and name it a real RPG.
To continue, a story is irreplacable. Without the dialogues the RPG would be bland. Deeds are a must since no video game exists where you don't have to do anything, it would be a movie. Consequences are the mark of an advanced RPG, deeds, dialogue options, exploring as well.