the levels,
The game itself is awesome :P i had lots of fun playing both versions of Doodle Defender (not that its rly a defence game :P) anyway, the level desighn is right of the bat boring... (even if its called doodle defender) and by randomly adding mines to add varation is not a good idea, because that makes some levels unpassable...
And if then the shop also happens to be 'closed' then your bound to die...
Yes, this could be good because it makes sure you cant keep playing forever and makes an end to your own streak, but not in a fun way.
Up to the point where i had to die, i kept seeing new enemy's show up, and that they where faster stronger and more dangerous, so they should be the limit to one's game, because that is somehow related to 'skill' and if you die like that its your own fault, and that is what the gamer wants, is it not? to test one's skill (or just have fun ofc :P)
so, to sum it up, random mines are not a good idea because of the unpassable levels, in my opinion.