In fluxx, cross-turn strategy is basically impossible, as the rules may completely change between turns. I've found that reading a book during other peoples' turns then just looking up and treating each turn as a completely new game is just as effective as tracking the game across turns and significantly less frustrating. So yes, there are rules, but only within a turn.

Furthermore, I was dismayed when I learned (upon first time playing) that "It's easy to get started: there are no rules to read!" actually means "you spend the entire game reading rules!"

I acknowledge that this is not a very social (and somewhat rude) way to play this social game, which is why I typically politely decline to play it.

Once you know what all the cards do, you don’t really end up reading them anymore. So, it’s a lie that there are no rules, but learning the rules is spread across multiple game sessions. The way we play other games, that’s roughly what happens with those games too. Games don’t “count” until we’ve all got a grasp of the rules.

You can plan strategy. Whether it’s more or less likely to be thwarted I can’t really say. I try to be flexible with a few plans. The main difference is you are more likely to be accidentally thwarted than in other games.

Calvinball at least has rules in the sense of physical laws still being in effect. AI Dungeon 2 doesn't even have that.