Check the forum post... Probably they will update the main website soon. I just installed the Mac version (sadly, it doesn't work well with my display)
Interestingly, when the game launches or exits on my mac, i can see my desktop flash briefly as it changes into and out of what looks like ultra-high-res mode, a kind of 1:1 pixel retina screen mode. I wonder if the game is rendering the oldschool resolution but then nearest-neighbor-scaling it to ultra high res for no good reason?
The new remastered version to be released in Summer is the same client as the normal version - I'm guessing 1.18 is actually here to test new engine for that release.
The Mac client runs at 1280x960 (double 640x480). The font in the menu looks like it's been upscaled or redrawn, but everything else is just pixel-doubled.