Have you tried adding mods to the standard version of CS 1.6? Do you want me to recommend some cool maps that you can add to an existing version of CS? It definitely becomes more fun, especially when there are new maps of different difficulties and new weapons. I'm currently playing the CS 1.6 Umbrella build, which I downloaded from
https://all-cs.ru/ , where instead of terrorists you hunt mutants, zombies and Umbrella soldiers. I also like the fact that the weapons here are changed to futuristic ones, for example, the classic AK-47 looks like the FN F2000, you can also download this build from the site and test it.