Windows API?!
So do I NEED to learn the windows API to be able to create hacks for games? I mean, isn't the windows API more c language like. Why do I need to understand classes then? Someone told me I need to understand classes before making hacks, but you can't even use classes in the windows API as far as I understood.
Overall, is it true, that I need to learn the old windows API that is a pain in the ass to just creating small programs?
Depends on what you are making. If you are making stand-alone trainers that are external, yes you will need to learn/understand the system API.
In some cases things that you code may land up not needing any API but it is still good to understand and grasp how to use them in the chance that you need to.
Classes are not required to make hacks either. You can create hacks in pure C which does not have classes and such.
As for you saying that the API is old, it is the system API. It is needed to interact with the system itself. But the need/requirement for them depends on the application.
For example, if you wanted to make a simple calculator, no you wont need any system API to do it. If you wanted to make an application that altered another applications memory (like a trainer) yes you will need to know/understand the system API.)