Especially compression. The compression provided by RAD Tools is nothing short of otherworldly -- it can provide compression ratios comparable to XZ, but with decompression speeds more along the lines of what you'd expect from gzip (or even better).

I hope that Epic does something interesting with what RAD has built here. Taking it more proprietary (e.g, halting new licensing) would be a huge blow for the industry.

How does it compare with zstandard these days?

Cbloom has a bunch of blog posts with charts purporting to show it doing significantly faster decoding than zstd at every choice of compression ratio.

I would trust him to run his own benchmarks fairly and properly, but I am not sure if there have been good independent benchmarks done.

Not just high-performance, his "Library Writing Realizations" post is also well worth a read whatever domain you're working in.

http://cbloomrants.blogspot.com/2015/09/library-writing-real...

Everyone who works there is extremely talented. Fabien, Sean, Allen, etc. Jeff has a very keen eye for it.

He's funny, too. Highly recommend The Jeff and Casey Show for podcast content.

fabien giesen, also at RAD, has a very informative blog as well. https://fgiesen.wordpress.com/

they have a seriously impressive group of developers

What were they paying to keep these greybeards around?

RAD always paid very well by gamedev standards. But that was never the main reason people worked there.

Some of the engineers are older but Fabian is in his thirties and last I checked his goatee wasn't greying.

AFAIR a public H1B entry from mid-2000 shows $300k salary, which was impressive at the time even for non-gamedev.

Thats insane for wages.

Work environment matters more than pay, and the pay presumably was very good. Imagine being down the hall from the people who literally started indie game development, or demo-scene royalty.

Interesting job with other people they like is probably a good guess.