How do you take a great game and ruin it? You start by not unlocking anything until your players reach a score they can never achieve, no matter how many bombs they put on the floor. You also give them useless guns and spikes that do nothing. Most importantly, you make it impossible to place the guns on the left side of the screen and difficult to put them on the right. Bonus points if you have the obligatory ads run between every round and don't let your players skip them for 5 seconds.
I almost wanted to pay for the ad-free version, but I had no reason to believe it would function any better. I hope there's an update coming with all the bugs worked out and a more achievable unlocking score.