Grinning Cobossus

Grinning Cobossus is an online 2D Flash vertical Shoot'Em Up game developed by Gama11.

Grinning Cobossus is a game that basically only consists of one level - which is a fight against the titular foe. However, this game features 3 difficulty settings (Easy, Medium, and Hard), survival mode, and up to 12 achievements earnable over the course of play. Will you be able to kill the cobossus?

This game can be played at here.

Tropes used in Grinning Cobossus include:

Collision Damage
Easter Egg: After you load up the game, right-click anywhere on screen.
Endless Game: Survival mode, which is unlocked after beating the Medium difficulty setting, goes on indefinitely until you fall to the Grinning Cobossus. For every iteration or loop, your upgrades get reset and the difficulty is raised.
Final Boss: The Grinning Cobossus. Of course, he's the only boss fought in this game.
Frickin' Laser Beams: One of the attacks that the Grinning Cobossus does in its first form is fire a giant blue beam straight down.
Non-Indicative Name: The Grinning Cobossus never grins or even smiles - it maintains a neutral visage throughout the game.
No Plot, No Problem: The only instruction you are given at the start of game is to kill the cobosuss. No other explanations to the story are given.
Point Buy System: After damaging the Cobossus enough, you obtain points that can be used to upgrade four of your ship's stats: Damage (ship's bullet power), Defense (ship's maximum health), Speed (ship's maximum speed), or Rate of Fire (ship's firing rate).
Regenerating Health: Your ship's health will slowly regenerate if its health is below the maximum possible.
Shout-Out: The titular boss of this game is a direct reference to the Grinning Collosus of You Have to Burn The Rope. In fact, even the ending links to a youtube video of the ending song of that.