The concept is here, and with some more fleshing out, I think it has potential. My issues are the gameplay, which is mainly just standing around and waiting. Energy production is probably too high, or should be off during the night. I had all towers at max level before the second wave even occurred. Once that point is reached, you cap off at 100 energy before night 2 is over and then have nothing to do for 3.5 minutes while you watch a countdown timer.