He has a page (in tumblr i think) where he keeps showing the (somewhat) progress and yes, as far as i have seen this thing (is not exactly a game, not a date simulator nor a visual or interactive novel so far) is still a demo, apparently (sometime) on the future he will finish demo 2 which will (apparently) will be (way) different from this.
This might be a demo for several reasons like:
Not having all the girls completed
Not having the scenario (the story) completed
Not having the whole island completed
Having to adapt the whole thing to VR
Others
A mix of the ones above and that (apparently) he is doing it all alone.
P.S.: The dude is also trying to improve the game yet keeping it as it is so those who could play on the demo 1 can keep playing the demo 2