Hey samthefireball,
The tech demos (1-3) are a playground to showcase the mechanics and expected gameplay that will be found in the final game but are otherwise unrelated to the final game in terms of the map itself and lack of story.
As for the full game itself, due to time and budget constrains this is only worked on part-time here and there and as such the full game's map and related is not yet in full production. However there are rough plans right now to move to full production hopefully within the next year and a half, during which a steam store page will be set up and Tech Demo 3 will be updated with a mini-boss and final boss as the full game is worked on. As the full game is worked on, there will be another demo containing up to the first hour of the final game.
I do understand that this is all taking a while longer than anyone would want, but it's for the best.
Development is not abandoned and the game will eventually release, it'll just take some time as I'm doing everything myself on a shoestring budget.