It's quite insane. A couple years back I bought and played an indie space game that had beautiful graphics, weather effects, 'splosions, space stations, hundreds of star systems etc.

That game's installed size? ~~260MB.~~ 186MB on checking.

The full game could fit on a CD-ROM about five times over and it was still many hours of cool gameplay. This massive universe exploration game is smaller than 90% of the 2D procedurally generated games I own.

Looks like they still develop, and still offer demos which I think is awesome. And their game sizes look still super reasonable.

I'm not really sure how you achieve that kind of compression, I assume most textures are hand-written shaders or something rather than 4k .png files.