After further playing I think that the main issue with this game is that the base turrets are more than enough for beating most of the levels. It makes no sense to spend money on the other kinds of turrets, except for the 4-shot one. You can just go with the basic ones and be ok... the developer should work a little bit on balancing things. Also, grids are almost useless in the first dozen of levels (and I suspect they won't become useful going forward...).
The 8bit graphics is ok, although i'd extend it to menus too (they are too sharp, in contrast with the in-game graphics). The game is ok, i'd say. Yet it is totally unoriginal. Luckily it is challenging enough, yet you should really think about something more innovative than a normal tower defense game. 3/5
Very good evolution over the first (excellent) chapter. Very creative and intriguing. The magnets are a very cool idea that works very well. A greatly deserved 5/5. Also, it gets very tough.
This game makes me fell very dirty! :-| Yet, very nica physics game. Not so much original. The very good art style made for the lack of innovation. Cool.
Way too rough. Art is very mixed, some elements are nice (like the hero and the aliens), some other are not that good (pretty much everything else). It is also quite slow. Did no like it much.