Yumil, I once made a game about magnetic objects (check
http://experimentalgameplay.com/game.php?g=484). From my experience I can say that it can be quite challenging for players to take meaningful actions and estimate the paths of objects wich are manipulated by gravitation/magnetism from a moving source. Thus my game became quite simple although my first idea was to create something like a shooter too.
Of course I don't want to scare you off, but I recommend you to build a simple but functioning prototype as early as possible for testing.
MAW
I can see where the confusion comes from. However, I think it's more due to the way the game gets harder than from estimating paths. It seems every level everything gets a stronger field, thus you push bubbles back further(not a problem), but you are manipulated by the enemies much more readily. It'd be fine, but your velocity starts getting quite high and makes missing some enemies nigh impossible in the high 20s. Really, I just felt like I didnt have too much control in it after a certain amount of bubbles, I was subject to the random enemies basically. It's still fun, but that amount of helplessness doesnt help it much:(.
It's just my opinion, but I feel the player shouldnt be manipulated by the fields to make a successful game. I'm of the school of thought that losing control of your player is no fun. So, the magnetic parts would all be for enemies, and if you really wanted to, you could just dodge them all, but those who like the game would master manipulating them. Course, a lot of this would have to deal with level design whether it ends up fun(placing enemies right when you put an innate field strength on them).
Anywho, back to prototyping. I actually do that to test simple ideas, however I have a very hard time making tools, such as level editors and what not. I guess it's due to me not having much practice with said tools to know how to structure one or the file format. Heck, the last tool I made was just a simple map editor in which I just stored the map as an array and the copy and pasted it into hard code to make my level file>.< Anywho, not being able to go to the next step or have something I can reuse really hurts me mentally as I'm always trying to think ahead as I do something(even so simple) and if I dont know what to do afterwards I have a hard time doing now.
However, Im trying Torque X builder(free with XNA creators club, so why not) right now, and though the builder is not all how I wanted(I cant change anything in it, its not WYSIWYG) and its a bit limited, I think I can at least use it to make prototyping a bit easier and give me an idea of what to do with a tool.
Thanks for the advice, and your little game is kind of fun, just cant get to the 30s in bubbles:P