Yes, i agree such games need some more work but i am talking about this game where most of its path is linear and short since most of the routes are unfinished and i guess it wont take a lot to construct.I am just wondering why he has not completed some paths even though it took years where most authors here create thousands of word per month and why people still subscribe to it even though most of the path is still the same as years ago
You are failing to grasp the fundamental difference between an interactive medium and a normal story. Sure, it's possible to write the same number of words, but for an interactive medium, the work isn't in the words, but in organizing the structures of each path and how they interact.
An important difference is establishing and writing scenes that are common anchor points between varying paths, as well as generally organizing all the different story branches.
I can tell you from personal experience making a Twine game that even two choices per scene can quickly lead to an extremely convoluted graph of scenes that looks like that meme where all the red lines are connected everywhere.
Also, if you're talking about Devious World by Skooma, it is
not as linear as it seems to be. The poor guy made the beginner's mistake of underestimating combinatorial explosion. I can guarantee that the work file for that looks like a giant tangled mess of spaghetti. I'd wager that most of the time being spent is sorting out that mess and figuring how to link the different choices back to a coherent story path for each branch and organizing it all.
I'd also wager that the project will never be completed in a lifetime considering just how it keeps growing instead of shrinking.
As to why people still subscribe to it... Well, SailusGebel said it best. Smut is smut, and smut sells, no matter the quality. People will do and pay quite a lot for their kinks.