Yeah - I imagine that the games are designed thinking most players probably have an SSD or - at worst - an HDD. An SD Card - especially a not-good one - can be 100x+ slower than an HDD for small reads. Any games that depend on this would effectively not be playable.

Micro SD cards are up to about ~290 MB/s for read times these days, IIRC. That's the same as low-end SSDs.

That's throughput.

IOPS is important.

For random 4kb blocks / second

SD Card => 2.1 [1]

SSD => ~200 [2]

[1] https://www.cameramemoryspeed.com/reviews/micro-sd-cards/

[2] https://en.wikipedia.org/wiki/IOPS

And that's comparing good SD cards to good SSDs.

As I was saying, bad SD cards can be REALLY bad. The difference can be over 1000x. Anything that depends on being able to read ANY small piece of information regularly in a reasonable amount of time from disk would simply not be playable.

That's assuming the games are writing to the SD cards and not the SSD though, right?

If this is Debian/Arch OS, I'd assume they are writing to a system folder.

No - those are random READS - not writes.

If the game is on the SD Card - it will be read from the SD card.

Sure, if the game needs to randomly write data to disk (I assume this is much rarer) - then it would write to the system SSD as usual.

Got it. So SD cards are optimized for large, continuous file reads, not varied file reads.

I'm not sure that's what they're optimized for. I think it's more of just that's how the technology works.

It's the same way I wouldn't say that film is optimized for storing lots of data with horrible access cheaply. It just happens to be what it is.

Used to play them fine on hard drives. Micro SD cards became as fast as them quite a while ago.