Instead of RPGs you should be playing adventure games. To me the main difference between the two is the absence of combat in adventure. They could be exactly the same game, but where an adventure game would have you throw a bucket of holy water at a vampire to kill it, the RPG would have a lengthy battle. Also one of the aspects of RPG is to see your character/party grow in power over time, which is hard to define and experience in a short game
Another possibility is playing Rogue style RPGs, which you can complete in a short time, but you're likely to fail many times and learn from your experience, like Faster Than Light.