I used to reverse engineer and crack CrackMes and CTF Challenges, and while those are fun and teaches important concepts it's not close enough for real world cracking. I'm looking for softwares to practice on. This will probably help other people so maybe we should make a list. I thought on something like:
Easy peasy software to crack (Closet thing to CrackMe but real).
Keygen.
Dll patching.
Manipulating server payloads.
Anti-debug bypass.
If you know any softwares that are suitable for this is great. If you have something to add or you think the order should be different then please update me.
First I learned how to program in c (recently I learned c++).
Then I learned how to read assembly, how pc memory works, what is dynamic and static linking, what are vtables, and for debugging I learned how to use tools like ghidra, Detect It Easy, xdbg, etc...
Learned about compression, un/packing, dll injection, anti-debug methods.
Also did some simple game hacking, nothing fancy.
It's not all but I can't write everything here... I don't know any good RE courses (maybe someone else here can share).
I also read a lot of writeups on reddit from r/ReverseEngineering and r/REGames
Have you done mobile, Android/apk cracking? Oftentimes these games have lower security, but I'm guessing it will be very different to Windows programs.
There's an infodump on cracking Denuvo by MKDEV on their discord channel. It's something only they and EMPRESS have done so far.
I think cracking denuvo is a long and arduous task but you can try the newer Football Manager (they only cracked those games) as it won't be much different and they already answer queries on their discord regarding cracking.
Cracking services is pretty dope for many people, but I don't know if that's what you are looking for.
I'm thinking of YouTube Revanced, but for Netflix, Spotify, all that. I don't know if you call that cracking, but it's definitely useful, and probably challenging.
Interesting idea but that's not what they're asking for and would be much harder requiring proxy infrastructure etc... many services are going online (service) only in large part because of piracy... you have to have a valid login and a way to access it without them being able to access the "crack" because then they'd just shut the linked (paid for) accounts down. OP is asking for a list of legitimate windows software that's licensed and has varying degrees of skill required to crack it.
OP, I would start with older software first. Like 2000's (2000-2010) releases from torrent sites that are already cracked... download a bunch of old programs and look whether they require a crack or keygen, run strings on the cracks/patches and you'll start to find certain indicators that something was easy to patch or hard, like strings indicating debugger check or http/s possibly indicating needing to intercept a server check. Anything that by its nature dealt with rootkit-type stuff like antiviruses, "spouse/kid monitor" software (legal keylogger/Trojans) will be more advanced and harder to patch. Small 1-3 dev org programs will probably be easiest but you'd be surprised.