the upgrading method works as intended, I believe. to encourage people to get pass a level with the minimum upgrades. so don't upgrade until you are unable to do it without an upgrade
this game is funny. you start the game at night and forget to turn off the speakers. then all of a sudden there comes a sharp and loud start up tone that made you rushed to turn off the speakers for waking up everyone in the house. right after that the next screen is "do you want to turn on or off the sound?"
I really wish the game ask me that question BEFORE playing the tone, you know.
anyone can beat level 57 in hard without hack... 58 is a bit hard but if you are fairly ok you can make it. anyone to beat level 68 in hard is someone truly good.
people who need to hack to get the badges are losers...
interesting enough, however too easy. hardly pull the trigger after level 3. All floors have a turret 5, a machine 4 and a laser 2. One with a laser 4.