Please check the troubleshooting guides before posting!

[repchi]

Hello, first of all I deleted your log. How did you do that with the 100 quotes? Anyway, next time attach the HPL.log file. Also, the one you copied above shows that the game exited properly.

1) Do a steam file integrity check and check if it reports corrupted files
2) Try the game and if the problem occurs again, reattach the HPL.log file

This is most probably caused by another program or service running at the background which closes the game. Maybe an antivirus or similar. Check the known programs that cause issues at Problem A4 of the troubleshooting guide. There are bound to be more though so make sure you also disable anything else running at the background.

Okay, to be honest. I just did a steam file integrity and it worked. Dunno why because it said that everything is alright.
Thanks anyways, LOL.