I hacked on C&C renegade online games.
It was stupid easy. You just used the official modding tools to create a project where you could define whatever properties on weapons or vehicles you wanted, exported it to a specific format, then threw that file in your game folder, and then you could have characters that cost no money, weapons that do 999999 damage, etc.
There was no official anti cheat software of any sort. There was a third party plugin that would kick you from the server if it detected added files, but you had to download and install the client on your own computer yourself, and if you didn't, all the game server did was throw a pop-up alert at you every few minutes asking you to install it
I went through a ton of MapleStory alt accounts too, but I only just fooled around in low level zones. I don't believe I ever hacked up to even level 30
That was back when I was like 12 or so, though.
Hacking online games and running other people's matches isn't fun to me anymore
a long time ago i felt really cool cause i used a cheat engine to make Blockland run really fast back in the free version before there was a timescale command (or maybe it was always there and i just didn't know about it until Retail)
There was always a timescale variable that the host could change via console. Just not a slash command until retail