Just posting this quickly as I will be off for 5 days or so and unable to access PC / work on game, so a little update.

• Got sound working, although it needs some tweaking I need variations for the sounds but the programming side is all done. I have a sound manager that pools sound sources, don't know if that is more efficient than putting sound sources on all the gameobjects. I also figured out how to put animation events on the animations to play sounds in sync (footsteps, sword etc).
• Made a couple more quick towers in blender, although there is no separate logic for the towers yet, they are all firing same bullets etc.
• Changed from using my native huts to some medieval assets from Unity asset store. As these houses are bigger than one grid square there is now a bit more complex logic for placing them, rotating them until they fit on the map. Also the waypoints now lead to the front of the big building which will be your base (I might change the building model though).
• And added some particle effects. Made a pool system for these, and got the effects themselves again from asset store. There are small explosions, smoke (for your base when being hit), flames, and muzzle flashes, and blood (although this is my old test particle system I made).
• Did a little tweaking to the area camera to make sure more of the relevant action was 'in frame'.

Although all the towers are firing the same so far, I will have them fire different projectiles at different speeds / damage / range. And maybe have some of the enemies attack the towers so you have to repair them.

I've got a feeling play balancing might be a bit time consuming at the end, making it not too hard or too easy and having it get increasingly difficult as you progress...