One of the best concepts I've seen so far. The issues with the buttons and the "surprise" that your towers don't have a range limit for your base has been addressed in other comments, so I will just mention that I share those feelings.

At the end of the day, this is a pretty interesting take on the tower defense genre, adding a huge economic element and reflex elements by making you plan on how to save and spend money so you can keep your own base safe. For that end I would make it clear how much money each enemy gives you. It would be helpful to know with a big number as they die or something in that style, because quicly counting the enemies and your budget is a huge skill here.

I think you derseve a spot at the top for Originality, as this was a great idea overall. The mechanical choices do need a revision, but hey, it's not like you got a lot of time to playtest, so that's understandable.

I actually really, genuinely love this idea. However, my only issues with it are A) the buttons for buying towers/upgrades just do. not. work. which caused me quite a bit of frustration, and B) the tower radius only applies to enemies? I'm not sure if that was intentional, but I feel as though it would be a bit more fair to the player if it was limited to the tower's radius, so that something placed on the front lines isn't sniping your base tower. Overall though, I really like everything you had to offer and would love to see this turn into something bigger!