green and violet squares?????

could someone tell me why there comes green and violet squares everywhere when i have played about 40min?

your computer is overheating.

They do kinda look like the artifacts that I sometimes get when my graphics card starts to run a little too hot... So yeah cooling is probably the issue.

thanks for help.

Yeah probably overheating, i suggest you check if you have a non-working fan or dust-covered video card before it overheats too much and give up you.