> I heard that Steam provides games for GNU/Linux, too, being proprietary
software (as I suppose it is), would make that unfree though, right?
Steam is proprietary and almost all of the games on it are proprietary. Those
that aren't can be obtained through other means.
> Are there any games like the ones I mentioned above as of yet for Trisquel?
That's why I asked. :) No libre game lives up to the standards of modern
proprietary games, but those that exist can be improved. I think you should
take a look at 0 A.D. in particular:
https://play0ad.com/
The rest of the games you mentioned are unlike any libre games that are
currently available (in particular, I'm not aware of any libre stealth
games), so those would have to be started from scratch. But here are some
other kinds of adventure games and RPGs to try:
* Naev: http://naev.org
* Nox Imperii: http://noximperii.com/
* Beneath a Steel Sky (package "beneath-a-steel-sky")
* Freedroid RPG: http://www.freedroid.org/
* Hexoshi: https://hexoshi.gitlab.io
Of course, you can also look at the Libre Game Wiki for other games:
https://libregamewiki.org/Main_Page
Where there isn't a libre game project that's like what you're looking for,
someone is going to need to start it from scratch. The most active thing you
could do to that end is organize a team, put together a techdemo, and run a
crowdfunding campaign similar to the one I ran for Hexoshi.[1] Being able to
contribute something significant (e.g. graphics) would be very helpful if you
want to take this route.
[1] https://www.crowdsupply.com/onpon4/hexoshi
