In Aqua Kitty Milk Mine Defender, you control a cat in a submarine, tasked with defending the milk mines from the robotic sea enemies. The map is cyclical, so reaching the far right makes you appear at the left, so you can constantly move the same direction if you want to, blasting anything in your path. The game-play style is fairly similar to bullet-hell games, although being set underwater and played horizontally gives it a unique style.
Your submarine has two types of fire. The primary method of attack is a weak projectile that has unlimited use, the secondary attack is a more powerful but limited attack which regenerates over time.
Along the course of the game, you are introduced to new enemy types. There are simple enemies that travel in straight lines, ones that move diagonally, ones that charge to your location etc and each of these have different rates of fire and varying types of projectiles. There is only one type of enemy that actually goes for the milk mines; the Jellygrab which grabs the cat and slowly drag him to the surface.
When your cats need rescuing, they let out a “meow” and the red dot flashes on your mini-map. You must then go to the rescue. Losing all your cats means game over, but you must proceed with care, because losing all your hearts also means game-over. The level is cleared when you destroy every enemy from the several waves of attack.
On the earlier levels, it's quite easy, but the difficulty soon ramps up. In later levels, there are plenty of enemies, so it becomes hard to weave around the bullets and the paths of the enemies. You can find that your health drains fast if you are not careful, especially since it's not that obvious when you get hit, meaning you need to keep glancing at your life bar.
Aside from the different enemy types and frequency, the levels themselves play out the same. You do get varying depths to the water, where lower depth means harder difficulty; partially due to the crammed space and due to the fact Jellygrabs have less distance to travel to drag your cat out of the water.
There are power-ups dropped by one of the enemy types which include health, an auto exploding bomb, and extra directional fire. The colour of this enemy cycles though the colours to show which power-up will be dropped if you destroy it at that time. You could follow the enemy until it changes to the power-up you want, but it is easier said then done.
There are 25 levels which can be played on Easy, Normal or Arcade difficulties. Arcade mode is Perma-death mode where you go through the levels without failing once. In this mode, the enemy that normally drops power-ups only drops the bomb. There is a new enemy that drops gems which are used to purchase upgrades or restore health. Restoring one point of health is fairly costly, so I found it was hard to compete more than around seven levels; it's a mode reserved for the hardcore. There's also an extra level called “Infinite Espresso” which is an endless survival level where you have no mines to defend; just fend for yourself.
I found that the more I played Aqua Kitty, the more I enjoyed it. It is short, so even if you play through a few difficulty levels and try Arcade mode, you will only get around 4 hours before feeling a bit bored.