On modern hardware, all games should be 60 fps. If they can't reach a consistent 60 fps, they need to start reducing graphical detail--fewer polygons, smaller textures, fewer lighting effects, lower resolution, whatever it takes to get the frame rate up. Frame rate issues were understandable in N64/PS1 and other early 3D games. After being accustomed to NES/SNES games where 60 fps scrolling in 2D games was fairly standard (not 60 fps animation, mind you, that is something completely different), I was somewhat annoyed by the choppiness of early 3D games. Of course, that didn't stop them from being great games. One of my all-time favorite games, Perfect Dark, has some pretty bad frame rate issues in the N64 version. However, on more advanced hardware (Gen 6 and beyond), it is fairly annoying to see developers push for graphical detail at the expense of frame rate. In short, I am a bit more lenient on frame rate problems in 3D games from Gen 5 (or before), since they were working with pretty limited hardware, but for Gen 6 and beyond I'll complain about it more. Of course, the older systems had problems with slow down (particularly SNES), which could be a little annoying at times, but you could also use it to your advantage so it wasn't so bad. Still, when there wasn't too much going on, the norm was 60 fps so the scrolling looked nice and smooth.

Checkered Flag on the Jaguar. THAT is low :P

I've been playing Elite Dangerous: Horizons for a couple of months with fps as low as 7 frames per second while prospecting on planets. It was a bit difficult to correct from a tumble, yet otherwise perfectly playable. As long as controller response is not tied for fps, I'll manage.

I had fsx locked to 18fps so it would not run out of land while flying. No problem at all landing a plane at 18fps, Boeing 747 or twitchy stunt plane. Too bad there is no option for 5fps, that's my threshold :p

I don't have any issues with 30fps but as long as I don't see the stuttering when it dips below that, it is fine (not sure what exactly that is though..)

Ever fight Crystal Snail in Megaman X?

THAT is too slow.

In certain genres a locked 30fps is fine but if the game is spending any amount of time below 30 (I mean more than i-2 brief stutters in a stage) that isn't really acceptable in this day and age.

Anything below thirty impacts gameplay significantly and indicates that either the game lacked appropriate optimisation or worse, the developer has favoured eye candy over gameplay.

It is.

The fourth option is "30fps is already too low".

If movies run at 24fps, why is it such a big deal for games to be higher than that? Just because people have been told it should be? 24 can still look and play just fine, depending what kind of game it is and what kind of gameplay and aesthetic the developer was going for.

This ignorant wave of gamers acting like frame rate and resolution are the end-all be-all of what makes a good video game really needs to stop, but only education can fight ignorance, and if they don't want to be educated, well...

Anything below rock solid 30 fps is unacceptable!

Even Bloodborne can be grating because even though it has 30 fps rate as a rule, the frame-pacing makes it jitter at times. Look to the newest Ratchet and Clank by Insomniac for how to create an absolutely gorgeous game, with satisfying gameplay and an incredibly stable 30 fps rate. If a game has a framerate above 30 fps, as long as it's stable, it's all a bonus.

Obviously 60 fps is the ideal and I still believe software-houses should aim for it, making concessions where possible.