Great genre mix (platformer/tower defense) with many interesting ideas. This game's difficulty level and its high speed made me sweat a lot. It was a very enjoyably hard experience, at least till I've reached the 20-th level and then the game became insanely difficult to me.
I have to say, that my three major criterions in any game analysis are the extent to which game utilizes its gameplay mechanics, how this mechanics interact with the story and artistic style to produce an integral aesthetic experience of a game, and how fun and interesting this experience is to me.
First off, this game has some fresh and interesting mechanic innovations. As I've noted above, I found combination of tower-defense and platformer elements very enjoyable. Gravity-switching mechanic allows to extract more advantage from two-dimensional flat platformer-like space by opening it's otherwise wasted verticality. Controls take time to adjust, but when they do, movement and navigation start to feel very natural. Turrets mechanic too does not work in a way one could have expected, and a player accustomed to more standard tow-def. rules (as me myself) could experience some hard times adopting to it. But after a few failed attempts I figured that this game requires more flexible approach to resource, space and turret managing: no penalty for turret deconstruction encourages players to shift their defenses according to the situation. Key to a timely turret management is good tactical and strategic thinking and precise spatial orientation. That's where gravity-switching platformer mechanics comes at hand, closing a circle of my description. Game's overall shortage of locations is compensated by the variety of ways you can enhance your defense’s efficiency: by combining different types of turrets, different locations, relocating turrets "on the move", shifting between locations, shooting enemies yourself, optimizing your shooting position, upgrading turrets, etc. Unfortunately though, shooting mechanics feel somewhat underdeveloped and most of the time pretty pointless; same goes for the turret upgrade system (in most tow-def. games player's choices oscillate between location and upgrades. here clear advantage is on the side of location, since you will rarely have enough resources to upgrade more than one turret, and at this point this upgrade will not do much difference).
Second, game's theme, music and graphics I found very well designed and quite fitting for the overall gameplay tempo and rhythm. Music, in my opinion, is especially important, since, while keeping player constantly on the edge, it creates frantic hyper dynamic rhythm that encourages player to move, think and react faster. Also game is very well visually organized. Interface is simple and clear, which allows more fluid and uninterrupted gameplay experience to occur.
Overall, playing this game was one of the most refreshing and exhilarating experiences I've had in a long time. It offers real challenge, while also creating some space for players muscle to grow, so to speak, and to achieve high scores through developing actual skills. With that said, this game also has some gameplay mechanics issues and definitely itself has some room to grow.