People interested in this might also be interested in OpenRA.
It currently supports C&C (Tiberian Dawn), C&C: Red Alert, and Dune 2000 and work is ongoing for Tiberian Sun.
For another oss rts engine that already runs multiple online games, there's springrts. It was originally intended for Total Annihilation so it tends towards TA-ish play, but many developers take it in exciting directions with lua.
That said, spring grew very organically and it shows. A fresh start like this probably has a lot of advantages.
Each open source project carry with it some model AAA game legacy. Starcraft 2 is for OpenRTS what Total Annihilation is for Spring, Age of Empire for 0ad, C&C for OpenRA.
For now, OpenRTS is specialized in micromanagement on cliffed/tiled terrains. All the game content is accessible from outside the code, using provided editors, XML and scripted langage. It is also Android (almost) ready. Those are the main differences with Spring.
Very cool!
My company is working on a tile-based board game engine. The thinking is that many tile-based games are so similar, all you should have to do is change the rules for piece-moving and you could start up a server for a new game.
OpenRTS team is currently working on a project using Entity System approach. This architecture will be certainly added to OpenRTS for much much much more extendability and flexibility.
I haven't seen any good systems on Github. We're making a very modular framework -- eventually a Javascript client & server could share the same .JS file for game rules, just swap it out.
Most of the game engines I've seen either do too much or are too specialized.
Just a heads up, but Games Workshop went after the vassal guys pretty hard when people started uploading 40k army stats. I would be very careful with anything GW related just FYI.
Not sure how it would go today (they're giving away licenses to anybody with a pulse and an iOS app on their resume right now), but back in the day they were very protective of their IP.
Hey thank you! I tried to open a vmod file but it crashed my terminal.. we're looking to make the rule-set human readable as well as machine readable with the above repo.
My point was not that it would mean there is existing code you can leverage--as open-source is exceedingly rare in games development--my point was that you are likely entering a saturated market.
I don't believe there is. At this stage what the engine really needs is a couple 3D artists who can help churn out a few more CC-BY models so that they can put together a properly playable game demo.
http://www.openra.net/