Story of a Cube (Steam key/Region free).

http://store.steampowered.com/app/440750
Take control of the Cube and blast your way through an abstract world full of danger.

Story of a Cube is juicy and fast-paced shooter starring a cube who sets out to take revenge on the evil circles who kidnapped his family.

Shoot.
Armed with a mysterious weapon left behind by the circles, you must fight your way through six challenging chapters. Shoot everything that moves and make sure to counter bullets with bullets!

Dodge.
Watch out for crushing spikes and other terrifying things as you navigate the maze-like levels and try to stay alive. Slow down time just enough to dodge the bullets coming at you from all directions.

Fight the Bosses.
Each chapter contains an epic, genre-defying battle that will be sure to test your limits. Get hunted by a swarm of missiles, avoid being crushed by the wall of doom and try not to explode.

Solve the Mystery.
Why did the circles abduct your family? What will they do with them? Will you make it out alive? Find out as the plot slowly unravels and you are faced with the horrifying truth.