Kingdom Rush is still at 4.2.15 on GOG, but on steam it's at 4.2.31. It's impossible to beat the game on Veteran due to a bug in one of the levels in current version.

Kingdom Rush Frontiers is still at 1.4.4a on GOG, but on steam it's at 4.2.31.

Kingdom Rush Vengeance is still not available on GOG.

I did raise an issue with both GOG and Ironhide Games Studio, but that was months ago and still no games have been updated.

I know that Ironhide Games Studio is a relatively small team, but is it so much to ask for an equal attention which other retailers like steam receive when it comes to keeping the games up to date?

You go tell them.

Я задавал этот вопрос в Steam на форуме. Ссылка. Меня проигнорировали. Спрашивайте тоже. Более активнее и публично! Пусть видят, что нас... не один, два и всё, обчёлся.

I asked this question on forum of Steam. Link. But I was ignored. Ask too. More active and publicly! Let them see that we are not just... one, two and that is it.

now it is updating...

...

Well if the game updates on galaxy you can be sure that offline installers will be updated this week. At least that is what always happens....At least it is a good sign that they finally decided to update the game.

Were both games updated on galaxy?

To what versions were they updated?

Don't own the game yet but according to some users there seems to be an update available in galaxy...If that user is not lying then hopefully it should be a recent version.
https://www.gog.com/forum/general/games_that_treat_gog_customers_as_second_class_citizens_v2/post1969

Yes, I can confirm that it is updated and all games are pure 64 bit concerning GNU/Linux with versions:
   kr1-desktop-4.2.33,  &160;kr2-desktop-4.2.33, and   kr3-desktop-4.2.15.

Other details with an overview for this series can be found here:
   * https://www.gog.com/forum/kingdom_rush_series/kingdom_rush_saga_technical_overview_gnulinux_centric