I "hacked" Cap'n Hector in Escape Velocity.
The game was shareware and he'd show up to ask you to pay the fee. After the trial period he'd start lobbing missiles at you. There was a basic editor you could open to adjust all the ship stats and weapons, so while you couldn't turn him friendly you could at least de-claw him.
I remember thinking it was weird how "easy" it was to work around, but it's hard to imagine the studio would care much: a pre-internet 14 year who loved the game that much is probably more useful as an ambassador than a paying customer.
I did something similar for the sequel Escape Velocity Override when I was a kid. It also had the same Captain Hector. Though in my case I buffed my own ship's armor and shields instead. I was not very good at the game (still am not to be honest), so I kind of needed that anyway to get through it.
I also remember that in EV Override you needed to stay below a certain amount of money to not trigger Captain Hector, and I would set the system clock back so it wouldn't think that the trial period had passed.
There are two modern spiritual successors to the EV games that might interest you if you haven't heard of them. Both are open source and have a decent amount of content (but aren't complete): Endless Sky, and Naev. Where the former is much closer to the old EV games in feel.
Also, if the game is single-player, you don't care: Simply let the players enjoy the game how they want to enjoy it.
That's true if it was just cheating.
But in this case I was hacking the shareware payment enforcement. Rather than shutting down completely the game would send an invincible and fairly destructive enemy (Hector) after you. It was really a clever trick from the developers to make the game mostly unplayable if you didn't pay after the trial period.
Ahh it didn't click that this was shareware enforcement, thanks. I guess back in those days developers weren't really fussed about payment, because paying was really hard (mailing in checks, and nobody had credit cards).
Many of them (us) made software for the love of it, and didn't care if it was cracked. I never got a single sale from my software but I didn't care.
Shigeru Miyamoto feels personally attacked by your comment :)
I gave myself a million lives in Super Mario and there's nothing Miyamoto can do about it!
He wakes up in the middle of the night in a cold sweat because of people like you /s