Library page says it's about 3 GB, actual downloader says it's ~11 GB. Why is this? Just curious, because it is taking FOREVER to install after an already-lengthy download and it's extremely tedious when I also want to download other games and I only have so much internet, so to speak. And when GOG still doesn't let me change download orders.

If the download was compressed and the unpackaged installation was 11 GB that would be one thing, but the store page and library list distinctly say it's less than 4 GB.

I downloaded it using GOG Downloader, and it was about 3 GB. The actual folder on my hard drive containing the folder is 11 GB. I'm guessing you downloaded it using GOG Galaxy, and it downloads uncompressed files for reasons of patching convenience etc. Still, it's surprising for a largely 2D game without movies and dialogue sound files to be so large. It also reflects in the loading times, they're really long for a game of this caliber.

It includes the art assets from the Seattle and Berlin campaigns for people to use in the editor. They make up a bit over 3 and a half gig. The Hong Kong assets are another 3gb on top of that. Then all the actual campaign data is another couple of gigs. It all adds up.

For me, the download was around 3gb (not using Galaxy or any sort of client; just downloaded straight from my library page on the website) and once installed took up about 11gb.

However, I was confused at the huge size compared to the previous games too at first, but as explained above: yes, the reason is that (except for music, sadly) ALL the art and sound assets from SRR and SRDFDC are included in SRHK.

That said, not all the scripts needed to *use* those assets are included (i.e. you get all the art and sounds you need for the SRR Insect enemies or the DF Pain Inducer weapon, but neither appear in the editor to utilize), but I'm actually working on a "restoration" UGC myself to fix that problem and make UGC creation using previous stuff (that HK already includes) much easier.