The full game is completed and has been for a long time, so this is just a demo and is gonna remain that way. The only way to get full game is, as far as I've been able to find, to subscribe to their Patreon. You cannot buy the full game anywhere, and the developers are most likely banking on the possibility that people might forget to unsubscribe which is absolutely disgusting IMHO. What's in this demo is good, but I do not tolerate bad these toxic business practices.