I love the Terraforming Mars solo mode but mostly play it digitally because for 1 person the setup is a lot. Since my partner is not as enamored with it, though, the cardboard version doesn’t get to see the light of day much. (Note: none of the addons are available digital as of now and there are at least 2 or even 3 that I really want in my game.)
I really like Concordia Venus. It’s a more recent variant that starts out with a different set of maps (the original maps can be bought as a separate expansion to the Venus game) and an additional god (Venus). It also has a team mode for up to 3 teams of 2. We haven’t played team mode yet due to Corona but I’ve enjoyed the flow of play and mechanics quite a bit. Beware though Venus is both sold as an expansion and as a full game so if you see a “really good price” it’s probably just the expansion. The theme is a little thin but the mechanics more than make up for that in my book.
We just finished the Clank! Legacy campaign at the start of lockdown. We enjoyed the campaign quite a bit–played it all with 2 players–and now have a personalized copy of the fantasy variant of the game. I hear good things about the SF variant as well. When I complained about the randomness of the market and the problems that arise from there being only “bad cards” out in the market I was told I should look at deck builders that feature a fixed market like El Dorado, Arctic Scavengers(?) and obviously Dominion. Anyway the interaction between deck and map is quite enjoyable and the closest to that would be El Dorado if you wanted a non-random market. Personally, I am also eyeing Aeon’s End (there’s already a thread about Aeon’s End ) for a coop variant on deck building with a fixed market and a few unique mechanisms.
I’ve recently acquired Viticulture myself mostly because the theme will get some of my non-gamer friends and family to play eventually. It’s a nice enough worker placement of medium complexity. I have yet to try the solo mode. I like the mechanism of aging the grapes and the wine and having them increase in value over time but none of the other mechanisms stand out to me. As someone else mentioned there is luck involved when drawing grapes, visitors or contracts and I’ve played one game where none of my grapes matched my contracts for several rounds and my visitor cards weren’t helping either. Good enough for a casual evening with a thematic bottle of wine 
I’d like to throw Spirit Island in here It’s worth half a debate if it is a Euro game but it certainly has some euro elements and luck is quite reduced. It’s coop for up to 4 but it plays very well with one player (playing 2 spirits usually) or 2 (personally I think it’s best with 3, YMMV) and it’s certainly on the more complex end of the scale though with familiarity the game turns into a fun puzzle.