Hey! Tried your demo!
It's definitely got around 80% of the stuff in place, but I noticed a few things:
1. Turrets don't fire bullets even though they track enemies.
2. No base HP displayed
3. Creeps when they reach your base does not disappear or attack, they just stack on top of one another.
Overall, I think you've done lots of hard work already in terms of making a great game!
I'm willing to help out as a writer if you're looking for someone to aid with doing tower descriptions, mission briefing, campaign storylines etc.
PS Your tower crafting game mechanism DEFINITELY needs some explanation, as I have no clue what to do :(