suggestion add better managers (for ridiculously high costs, obv.) that increase the rate at which profits are produced instead of increasing the profits.
absolutely awesome game, difficulty increase of each level exactly right (although i dread to think about how hard lvl 20 is going to be.....
i'd give it 5/5 but i expect the finished version will be far better.
nice game but a bit too easy for my liking. by lvl 16 I wasn't having to use my main turret at all.
Hint: build a fwew heavy turrets all next to each other on one side fairly early then just focus on getting all the upgrades. when fully upgraded, surround yourself with heavy machine guns, rocket launchers and lasers.