Cheat Engine

[FreeER]

haha, when you figure it out be sure to let all the game companies paying for things like Themida and Denuvo know so they can pay you instead.

In other words, it's really really really *ing hard to truly do so. To start out don't use CE to generate your trainers, it's open source so it's easy to look up how it works and undo it (and people have created programs/scripts to do so already). Don't use a language you can't compile, and don't use a language like C# where you can easily pull information from the "binary". Use something like C++ to write it, then google for basic anti-debugging code and obfuscation techniques and tools to make it harder.

Or if you can bring yourself to do it try using an interpreted language that's naturally obfuscated like lolcode or brainfuck (see https://dzone.com/articles/most-difficult-and-strangest-programming-languages while they may not be interpreted or originally intended that way many likely have interpreters people wrote for fun). You want it to be interpreted and not compiled in this case otherwise they'd have normal assembly code to work with and that's a hell of a lot easier to reverse than the language itself lmao