I would hardly call this a puzzle, though that might just be me. I have solved 1-25 in one try, pretty much constantly moving or waiting for the next platform to land. More of an easy platformer.
Tip: get something like level 3 in all starter gun stats, and you can take down the 1st boss in a matter of seconds. Get high (10+) multiplier and take him down fast for lots of easy money. If you are a ninja at top-down shooters, take no damage for double money.
Tip: 3 slot ships are REALLY GOOD - triple the damage of a 1 slot. Some good guns to pair with them are energy cannon, frag bombs, gatlin, pig and meteor (in order of how to buy).
There's another ship that is 10% the seeming intended cost, the Triumph. Also, you should make slots 100x in "total value" and speed 10-50 times, just so that the values are more accurate. I'd take 3 slots 100 armor over 1 slot 200 armor any day.
Hint: Range is actually a square. To dev: NEVER sacrifice function for graphics, when you are basically choosing: Should I make this graphic look good or make it fit it's purpose? The circle made me lose battles because of sub-optimal placement.
@me@silent: Also, if you meant the "win, lose or..." stamp you can try a health-ful unit with ranged that whittles at enemy health, then skips until they are almost dead, then pulls out a heavy one-hitter. This gives you a decent unit that has a large window of opportunity.
@ outlaw: Are you new to english? You don't need to capitalize every word. Also, I enjoy fighting for my stuff. It's a well designed game if the dev is trying to make it a challenge for a tactical mind, rather than another lag-tastic tower defense. I enjoyed the ability to lose towers. The quality is really minor, many games can't use it. You can go to the menu to restart, Monsters don't go through barriers as far as I can tell, and turrets are upgradeable to deal tons of damage.
Note to dev: The game is good, but it gets really boring after awhile of grinding the same enemies, though the difficulty is probably just because I'm on a laptop. Could you make it less grindy, either by giving more money, lowering enemy health or some other ingenious idea?