I know the "defeat the castle" objective isn't that abvious because it has no health bar (which I'm working on and it'll be added to the post-jam version), but I don't know how I could make the camera control move obvious then literally writing it in the controls.
I know it's not original, but my friend insisted on making a reverse tower defense game and it's a gamejam entry afterall we didn't want to waste too much time on coming up with an idea :P
You don't need to be absolutly original. You are making a good work, so keep it up! :)
Advices for postjam:
About castle - either add health bar or make castle more destructable (less health or visual feedback of it's destruction)
About camera. I recommend you to either cut this feature entirely (making smaller levels that fit on one screen) or redo controls - add arrows at the sides of the screen, and allow control camera position with cursor (just like any RTS do it)
