"the industry" and participation in it often assumes certain validations. questioning those may not be healthy for industry participation but may be healthy otherwise.. ymmv.
for instance.. "what is fun and ought it be done?" and "does fun actually exist?" are implicit parts of my creative process, but not for those who assume that fun certainly exists and generate income by tailoring towards this definate objective.
..what i am suggesting is that the question you have may be because you are currently integrating "game making" into your life, and life is a wider set of values than those presented by an industry. now you can make a game.. but what exactly is fun? (others have answered this, and i maintain that "fun is an activity one is encouraged to participate in without a definate idea of the objective," eg. the manner in which children are encouraged to participate in "fun" activities to develop skills, keep them out of their parents hair or whatever).
as an "old" person easilier accustomed to putting on a year or two than in youth, i often keep a project in my thoughts for a few years and see how the ideas develop - incidental life events can easily translate to fantasy settings to inspire storytelling devices/plots. actually, it's easier to find a linear progression through related themes (a linear progression is at least some form of creative aggregation) when you've got a lifetime behind you.. one can pull from various experiences and feel "confident" about them because they are real... otoh if you are young, creative ideas constantly have to be weighed against the idea you have of what your peers will expect, as that may be your working model of "what's good enough".
ultimately, are the ideas good enough for a game? here again, life experience can jade.. as one sees new releases as less appealing and more often hackneyed assemblages created for capital gains or other rudimentary thoughts. it's "harder to answer" because at my age i wonder next, is a game good enough for me? ...... when i was young, all the tech was new, but later in life it's more of the same.. so very often, when i get these ideas for creating a fantasy world, i decide instead, to put the energy into living my real life.
it's like i have a friend on facebook from anniston.. every post about game development he says "call the cops.." because i guess the anniston idea of a video game is getting the cops to chase you...
if you get away, it's probably healthier than carpal tunnel :)
you get one shot for every moment at making things or not making things, and our choices define who we get to be. i spent a bit of time reading about what makes games or stories compelling but was pretty happy with my own ideas about it. one of my favourite game ideas is "octodad," but i seriously can't see anyone sitting down and cooking up an idea like that.. i can only see it being birthed in the hot forges of semantic motion.. ideas flying around and for an instant two things click together and you realise it's exactly right.. (this idea expressed in a fritz leiber short with an extremely silly name) or basically i mean come on wine? ale? culturally, who writes this stuff, "hempen rope".