Technically, any game with different outcomes for different choices could be considered an RPG. If we were to look at the subject mechanics-wise, RPG is a game where you build your character. How long does this building go?

It depends on the game. In a classical RPG like Fallout or Baldur's Gate, you can fully customize your character from her looks to her skills. In games like Gothic or Witcher (which is an action RPG), you can't change the look of your character (you can change the hair/facial hair of Geralt, but he is still Geralt). You can still adjust your skills to your liking. Are they RPGs? Yes and no, depending on your understanding of an RPG (Excluding the first game, I wouldn't consider the Witcher series as solid RPG entries, sue me).

Take Red Dead Redemption 2 (or Red Dead Redemption). The game is all about feeling like a cowboy, and your decisions change the game's outcome. Sure, you can't build your character or change his name, and you gain no skill points, but can you say you aren't role-playing? Looking at the game mechanics, it isn't an RPG. Looking at your actions' effect on the story, it's an RPG-ish game. Sorry for this ugly sentence.

The last entries of Assassins Creed have adopted the skill-tree mechanics from RPGs. Are they RPGs? They shouldn't be, but you build your character in a way, don't you? All we know is that the RPGs in the traditional sense are dying. Some new games try to keep the genre alive, the number of those decreases day by day. Hats off to Disco Elysium and Pillars of Eternity.

The motivation of implementing RPG mechanics in new games is about enhancing the feel of progress. The implementation is NOT for the sake of role-playing. That's the reason we see so many non-RPGs with skill-tree systems.

Okay, we can't pinpoint the exact moment when people first played a role-playing game since pretending to be somebody else and telling believable lies for fun is probably as old as humankind. We know that storytellers have existed for almost the entire history of humanity. If the purpose is entertainment, something as simple as mimicking an animal or doing a historical re-enactment could be subject to the role-playing game. You see, all the confusion about what RPG is and what not is that the definition of RPG is relatively broad—man, trying to break down and define a concept that evolves and changes over time… I hate metaphysics.

And I'm probably getting ahead of myself. For the sake of our article, we'll go for the next best option, that being what is considered the ancestor of role-playing games in the current sense: Dungeons & Dragons (D&D). Derived from wargames —nope, I'm not going into that hole— D&D was published in 1974 by Gygax's TSR. This pen-and-paper game gave players freedom limited with their imaginations, and of course, the rulebook. Rulebook consisted of weapon types, races, skills, etc., but players could use these however they like. There was never made a game so imaginative and yet so grounded before. People fell in love with it.

Even though TSR aimed at a niche audience, the tabletop RPG (TTRPG) craze spread like wildfire. Inspired by the success of D&D, new TTRPGs have been released. Some of the notable titles are Tunnels and Trolls, Empire of the Petal Throne (1974/75), Chivalry & Sorcery (1977), RuneQuest (1978), Metamorphosis Alpha (1976), Superhero: 2044 (1977). Empire of the Petal Throne and City State of the Invincible Overlord.

Today, adventure games are more robust and diverse than ever before. Developers continue to release sequels to earlier hits and introduce new titles. There are now adventure games for every type of player, from those who prefer to relax with a light-hearted game to those who want to be challenged by a complex and thought-provoking story.