-Free Stars on steam, used to be called Star Control 2. Old school space adventure. And it is literally free as well. -Imperialism 2 on GOG, 4x game set in the age of exploration and industrialization. -Civilization 4, the best of the series in my opinion, I’ve played them since the 90s. -Beyond Good and Evil, comes to mind, don’t remember much about it, except that it’s good. -To the Moon, indie adventure / puzzle game. Has great reviews by the developers aunt, among other things. -Banner Saga 1-3, holy Nordic inspired epic tactical strategy, batman. -Jagged Alliance 2, another tactical combat game, modern time, funny, realistic and really difficult.

Eh, realized that only the first one is free to play. But the other ones are old (or very old), so you can snatch them on sale on steam, GOG or Epic for less than a chocolate bar and get dozens of hours of enjoyment from them.