Last time there was a sale was on WinGameStore in april (?) giving a Steam key. However, that was likely not triggered by the dev, but a sell-off of existing keys I believe. The last GOG sale was in May/June 2021, if I remember correctly.

Last sign of life I have seen mentioned on the steam forum was december 2021 when someone sent in a bug report for their other game DX-Ball and got a reply. But well, it's sad to say, at this point I wouldn't really expect any more updates or even info from the dev. There might be a surprise, of course, but it seems the studio has somehow shrunk to a one person thing and that one person is now completly overwhelmed with everything and maybe even gave up (but we don't really know for sure).

That being said, the game is totally worth it even without a sale! (if you can afford it of course, everybody's situation is different after all) - Also some great mods are available for GOG users in ModDB.

I think a sale needs an active studio to trigger it. But Longbow seems to be dead sadly, and i'm relectutant to buy a game full price, that may not have been fully finished (i.e. the final expansion that was announced but left in limbo).

It is nontheless said to be a good game, but personally i'd be more inclined to go for the steam version due to having easy access to workshop where people have made some impressive mods. I'd also recommend getting Hegemony Wars of Ancient Greece, which is the first game of the trilogy and very good, if perhaps a bit dated visually.