Played the game for a solid hour before my laptop decided to conk out for the day. I'm glad to say that I like the game, and the concept in itself (a card-based tower defense game) was unique enough for me that I'd give it a fair shake.
Some issues I feel that the game needs to address: the matter of cards being more or less the determinants for the kinds of towers you are able to use. They're fine, but I'd honestly love to see more variety beyond 'Card A hurts enemies at once' and 'Card B converts this Tower X to [Insert Elemental Damage Type].' Some would feel that they're uninspired, but as far as tower defense games go they're standard enough that using them to give genre tropes a new spin would undoubtedly boost the game's popularity. The game being 3D is nice, but I don't know why there's a need to put the maze in an if the player won't be able to interact that much with the background to begin with. Maybe limit the camera's view to a cube just slightly bigger than the map?
Audio and visuals are nice (especially considering that this was a one-man project). I would love for more people to support this financially, because (and speaking as a fellow dev) more support means the dev responsible for this game can maybe hire artists or even purchase assets commercially and readily available for use. I can understand, however, why some would feel that this game isn't worth the $5 price tag (not the heftiest of prices, but some people determine worth differently). I paid for this game because I want the developer to continue improving on their existing product -- it even says on the tin that this version is pretty much just a demo. Who knows what they could do if they had a bigger budget?