Right now, we've finished most of the core features in our game and we're currently working on getting mobile-specific features into our game (online leaderboards/IAP), starting with Android.
First up, here's one of the music tracks in our game. It's the stage BGM, and you'll be hearing it the most as you play the game. Check it out here and let us know what you think!

:
https://soundcloud.com/ninjetost/cool-neon-asteroids/s-sN8exAs promised, here are some in-game screenshots of our bosses, including the 4th boss.
The green crab boss

The 6-eyed boss uses its small eyes to fire laser beams at the player, and opens its larger eyes to fire bigger laser blasts.

The giant fly boss sends out 2 flying bug turrets to annoy the player, while it deploys time bombs that will explode if you don't destroy them before their countdown reaches 0.

Although you may face the 3 default bosses at any point in the game, you will only face the 4th boss if you are able to defeat 6 bosses (i.e. 2 boss cycles) in a single playthrough. The 4th boss has been designed to be the arch-nemesis of the
Ninjet, hence we've decided to call it
"The Shinobot" 
. As you will see, it can also transform between robot and jet forms!
This is what the Shinobot looks like:

Here's a few GIFs of some of the Shinobot's attacks as well:
Bouncing spinning blades, shurikens, and jet mode rapid fire

1st desperation move (activates when health goes below a certain %): Shadow clones + Shuriken attack

Final desperation move!

That's all for now. Will post another update soon!