I had the exact same problem not long ago. My old CS 1.6 version was installed years ago and apparently included outdated launcher files and modified settings that no longer worked properly on newer Windows systems. The game either crashed immediately or closed after showing a black screen for a few seconds. After trying many random fixes online, I finally decided to completely remove the old installation and download a fresh version from https://csnation.net/. That solved the startup issue immediately. Counter Strike 1.6 launched normally without any extra configuration, and I also noticed much better stability during gameplay. The build felt clean and lightweight without suspicious software or unnecessary modifications. If your current CS 1.6 installation is outdated, replacing it with a fresh version from there is definitely worth trying.
