With the pandemic lull, does anyone have ideas for free, in-depth games to play? 0 A.D. comes to mind for me.
Edit: also GOG: https://www.gog.com/partner/stay_at_home
Easiest to get up to speed in the "minstagib" or "instagib" mode, where basically one shot kills and "bullets" arrive at their target instantly. Once you're familiar with the mechanics, the other modes are quite fun, too.
[0]: https://xonotic.org/
So I would skip the free to play games if you don't have a budget for them.
My personal favorite free and open-source game is OpenTTD but it's a bit dated.
If you're willing to shell out $6, I can't recommend Sid Meier's Alpha Centauri enough, especially if you're into turn-based civ games. GoG has a ton of older stuff for less than a Hamilton. https://www.gog.com/game/sid_meiers_alpha_centauri
"Mindustry is a hybrid tower-defense sandbox factory game. Create elaborate supply chains of conveyor belts to feed ammo into your turrets, produce materials to use for building, and defend your structures from waves of enemies. Features include a map editor, 24 built-in maps, cross-platform multiplayer and large-scale PvP unit battles."
I don't think my picks will be similar to 0 A.D., but some interesting ones that stick out to me are:
https://alt254.itch.io/triforce
https://namatakahashi.itch.io/i-want-eat-the-sun
https://seregsarn.itch.io/taraman-castle-oni-story
https://aetherinteractive.itch.io/sol-hemochroma
https://minkcv.itch.io/urbansnake
https://cyangmou.itch.io/fantastic-fetus
https://co5monaut.itch.io/do-not-take-your-eyes-away-from-th...
The Dark Mod: https://www.thedarkmod.com/main/
S.T.A.L.K.E.R. Anomaly: https://www.moddb.com/mods/stalker-anomaly
Rocket League
Counter-Strike: Global Offensive
Team Fortress 2
Starcraft 2
Fortnite
Diabotical
Disclaimer: Still in beta. Move around to fight people.