okay, so apparently Atari bought rights for Transport Tycoon Deluxe and it's now available on GOG and Steam
meaning the original game is no longer abandonware
i guess for some reason, the #OpenTTD dev team has decided that (even though their product no longer depends on TTD) they can't offer OpenTTD as a standalone game on these platforms? it's bundled with regular TTD now
(worth noting that OpenTTD remains free and open-source on flathub, in distros, and as a regular download from the website, but still weird)