We're doing small teams.

Sid Meier's...

Don't think that any of those with that naming style were actually just made by him, or him and one other person even. Probably only his earliest handful of games would fit that, and not sure whether those would fit under great (though for their time... maybe?).

Kenshi, aka my current obsession. I'm surprised no one has mentioned it so far. Plus it's big, no idea how he managed to make the map this big by himself, before even populating it. It must have taken tens of thousands of hours in total.

And in the later ones he has had a minimal involvement, if any at all.

Just wanted to chime in and back the dev up on this. It might have looked sketchy that noone but the dev himself spoke up for this game, but I only just discovered Caves of Lore by accident, less than a fortnight ago, bought it not knowing what to expect, and it truly is impressive, a hidden game if you like oldschool RPGs. I'd say as fun as Knights of the Chalice, at least (a bit easier and better priced, in any case - particularly at the current sale price). The game still gets regular updates and support from the dev, too.

SpaceBourne 2 might fit here.

Northern Journey was made by a single guy.

Those are not made by a single person, but by different persons! Who is this single person we are talking about here anyway?

Doesn't matter anyway, soon AI will make us new games. Boy, can't wait! The human(s) give only the concept to the AI, like "A first person shooter set into the zulu wars, from the British point of view", and the rest is history!

Ostriv
The development of Ostriv began in the spring of 2014. At first the game was developed by one person. Since 2018 the game has been developed by a team of 4 people

Mount & Blade as i remember was made by family couple and released as indie title. Maybe family can be counted as one unit)).
ps - digged a little, seems like they created small company, and had money enough for 1 year of development, and then returned to work to supply the process. So it does not comply to this topic, but is an honourable mention.

Early Ultima games were made by Richard Garriott.

I believe the early Wizardry games were made by Andrew Greenburg and Robert Woodhead.

Of course, later entries in each series ended up being made by sizable teams, but they started with just one or two people.

(Note that this isn't counting playtesters and support staff.)

Tunguska: The Visitation gets updated so often that I use it as an indicator of whether or not GOG's blue dots (offline installer update notifications) have broken for a 150th time or not. Sometimes it gets updated multiple times a week lol.

Rotorist also puts other developers to shame, who complain how difficult it is to keep GOG releases up to date.

Heard that Caves of Lore also gets frequent updates. I just bought the game over the weekend and there's already been a blue dot since then (on Monday).