Hello :)
I suggest you to take a look (and even create an account) at the official Xenonauts' forum here ;)
There is a mods section, where you'll find a lot of very good mods, and steam workshop isn't required in any way as far as I know ; the game is made in a way that mods are easy to put into the game and to activate/deactivate according to your wishes (usually).
Here is the specific section of the forum you're looking for.
Have fun :)

Thanks for the quick reply and the direct link.
Of course the Steam Workshop isn't required for anything, but I wasn't sure if the modding scene put out stuff outside the Steam Workshop or not and how big that scene was.
I guess I'd like to know how much of the steam workshop stuff is available outside of it. Luckily steam doesn't have a complete monopoly and games usually have the majority of mods available outside the workshop. Is it the same with Xenonauts?

You're welcome ;)
As far as i know (I can be wrong), the modders are mainly in this forum, and so are the mods projects (even if you can find some of them on the two "platforms"). (I finally found again this small thread :D)
Yes, it's the case for Xenonauts : I'm using only the forum I gave you links for looking for mods. May be I'm missing some mods the forum may don't have, but the forum's community (and modders) are very active and usually helpful, and there is a lot of high quality/very useful/very interesting mods on the forum and I don't even feel the need to go take a look at Steam workshop. So for me, here the steam workshop is absolutely not "needed", even as source of mods :) (and I'm glad to see this for Xenonauts :D)
I hope I answered your questions :)

I'm recommending Skitso's Ultimate Megamix Map Pack 2000, the Enhanced Crash Sites mod and the Fire in the Hole! mod.

sorry for bringing this up after some time of inactivity but i couldn't find any info anywhere.
all the links that i have found online for the xenonauts mods (community edition, etc) and for the official forum for xenonauts (the goldhawkinteractive), direct me to invalid link pages and i can't find any xenonauts threads there. does anyone knows what has happened and where we can find the mods that were there (like ce 0.32).
thank you

No problem for this, especially if you've a related question ;)
It seems that for now the official website is down, and the forum is down too (it leads to a wrong forum). So the best is to wait the time all of this is solved !

thank you for your reply Splatsch,
i hope this is a temporary thing, and the goldhawk forum be back soon!
i'll give it another try in a few days, see if anything has changed.

You're welcome ! Always a pleasure to help !
Everything is back to a normal situation, you can go download the mods ;)

Indeed it is! that's perfect! :)

Are there any other recommended mods besides the ones listed by PaterAlf?

Xenonauts Community Edition (CE). Should be possible to find this via the Xenonaut forums - I believe it has its own section there.

Currently there's a chunky "mod pack" that is recommended to install with CE. All of these extra mods can be enabled/disabled at will of course, though most start enabled. This includes a significant amount of balance mods, lots of extra maps (and they've adjusted the way maps are selected such that every mission you should have a unique map), lots of other (minor) tweaks/fixes, and more/improved lore (e.g. Xenopedia entries).

Also includes "Armored Assault!", which modifies vehicles substantially - though it's disabled by default.

If you want mods from Workshop, just go to the mod's page and copy the link then paste it here: http://steamworkshopdownloader.com/

It'll download and then all you do is put it in proper folder.

I'm looking at this page here, for the Community Edition mod:

https://www.goldhawkinteractive.com/forums/index.php?/topic/14516-xenonauts-community-edition-0343/&page=1

Does anyone know how I should set it up such that GOG Galaxy launches the Community Edition?