XSp.

Bulletsss an interesting platformer-puzzle game made by indie developer Arvi Teikari:

If you think you played something similar to this previously, it’s probably Bulletzorz, the prequel to Bulletsss, also made by Hempuli (Arvi Teikari).
You basically have to reach the flag using a gun that shoots huge bullets to help out.
While testplaying it, I kinda got stuck in an early level… but it’s pretty nice and challenging.
Click the image or this link to the official Bulletsss website.