way to hard
you don't start off with a lot of money and you are only limited to 15 soldiers on the field. That is unfair. The enemy gets a new soldier every level and is able to have any amount of units on the field. There should at least be a way to increase the amount of money you can get withouth waiting forever to scrounge up enough money to buy an upgraded powerplant, upgraded resedential building, and upgraded bank. By wave 5 they already had 3 light tanks on the field and i was barely making my first one because it takes to long to train the units and to buy the facilities to make them. How are you soposed to protect your city if you can't get your units out on time?
You need to make the income faster, the unit training faster, and the enemy slower in upgrades.