Thanks :D I made most of the game in a single day, so didn't have the time to think of the idea :)
There will be a second version of the demo and then a full release, I will change the game with your feedback in mind :D
(I use unity btw) I changed the resolution of the screen and then turned it to a material, then assigned this material to an object, that's it :)
Here is a tutorial for in depth explanation