"The first time we showed that game internally it had wizards
and castles," recalls a smiling Castle. "We were working with
Virgin at the time, and they said that they had this great IP,
Frank Herbert's Dune, and Brett loved the books. So we took
the game we were working on and recreated it in the Dune
universe.
"It solved one of the fundamental problems we had with making
an RTS, which was that we wanted to have a central resource
that everybody was fighting over. Dune has spice, which made
perfect sense - and it was also used when we came to the idea
of tiberium. It became the anchor of the C&C universe...".
There's Airmech, an alpha version is available for play on Google Chrome. I think the developers intend to make it into a free2play game, like Leagues of Legend.
How about Command HQ and Dan Bunton's games http://en.wikipedia.org/wiki/Command_HQ. I'm pretty sure Ancient Art of War predates that though. I'm showing my age.
You can probably make StarCraft in the browser, too. If you remove the nostalgia filter, that's a much better game than Command & Conquer. (I enjoyed both back then.)