Seven Kingdoms: Ancient Adversaries, a proper classic RTS that's open source continues living on with a fresh release now available to download.
Originally released way back in the 90's, Enlight Software later decided to open source it in 2009 and since then it's seen quite a number of updates as well as a Linux port which works rather nicely.
Here's what's new in 2.15.2:
- Fixed queue buttons in the Harbor and War Factory, and in the tutor dialog for the non-blocking button code.
- Fixed AI crash when trying to use a skilled unit that has been deleted.
- Added German, Portuguese, and Spanish translations.
- Correct mobilizing other nations spies in firms under your control.
- Fixed AI crash when fort being used to attack has been deleted.
- Fixed crashes on bullets hitting targets due to not being attributed correctly.
- Fixed crash when a seat of power is destroyed at the same time the greater being casts magic.
- Fixed AI use of uninitialized memory when defending a general or king, which can cause a desync.
- Added mouse wheel support for map scrolling on touchpads. (sraboy)
- Added scenario completion tracking. (sraboy)
- Fixed crash in automated attack helping where one unit selects a target, the target unit enters a building (or deleted), and the local team then tries to assist, but the target unit is no longer on the map.
- Added advanced config file support. This will allow changing more aspects of the game without recompile.
- Enabled sync checking in replay mode.
You can see the official site here.
7K:AA was actually one of my earliest RTS games, so it holds a special place in my heart and I love that a community has built around it. I used to spend entire days playing this, which is somewhat amusing to think on now considering how basic it is compared to a lot of modern games. For the time period though, it wasn't even revolutionary and came up against other amazing games like Total Annihilation and Dark Reign, even so it's still fun.