Yes I did. I regret buying a handful of games on Steam (or GamersGate) that later showed up on GOG, although they were very cheap, so the regret is relative.
I regret more buying a couple of games on CD-ROM that were also subsequently released on GOG. Those weren't as cheap, though I could always try to resell them.
I could also add some games that GOG gave away for free afterwards, even before I had played them. I could have saved some money... but maybe that would be too much complaining!
And, going back to my C64 days, I could probably come up with some titles, too...

Same here. Well, "nauseous" would be a bit too much, actually... let's say, the game just didn't "click" with me. After a while, it became very cumbersome to play... I ended up abandoning it, and I can't see myself returning to it, sadly.
It's the one game I'm most sorry not to like, but hey, there's worse.
(To be fair, I dropped Gothic as well... "open world" games are just not for me, I guess. Though I'd actually like to resume that one day).

Yeah I could say the same. I regret even more not buying a bunch of games that haven't seen a sale in years, back when they were discounted, or whose price cutoff during sales is much lower nowadays than in the past and are thus way more expensive now than just a few years ago.

That's my rule as well :)

never pay more than 10 USD
never preorder
never do Early Access or paid alpha/beta
never do always online DRM or cloud streaming
never do amazon luna
never put money in fortnite
never pay for some license that can be revoked through no fault of your own

I got a free review copy of Fire Warrior on PS2 before it was released in stores and even then it was disappointing.

Of course. Many games that I didn't end up liking. Many games that showed up on bigger discounts before I even got around to playing them. And some games that I know I'm never going to play in the first place.

Yeah, the other rules as well. Even though I have no idea what Amazon Luna is. And I wouldn't put money in any microtransaction whatsoever, not just Fortnite.
I forgot to add, my 9.99 € limit is for digital games only; I'm willing to spend more for physical copies... within reason.

Now that's a game I'm perennially on the fence about. I think I could probably enjoy it, in a trashy kind of way maybe, as I like the setting, the genre and the time period it came about, but I just can't bring myself to buy it, even for under 1 €, as opinions are all so bad...

That's a possibility, too, as I certainly tend to buy more games than I'm going to play immediately, though perhaps less so nowadays than in the past. Same with books, and music.

Amazon Luna is cloud streaming gaming, similar to what google stadia was

other than that support free software (open source)