I've always thought the sci-fi universe seen in Quake 2 and 4 would make a strong basis for an RTS. Whereas the original game's setting is a hazy mix of fantasy and futurism that emerged from its troubled development, the sequel had a much more coherent identity. Its interstellar war between human soldiers and Strogg cyborgs felt incredibly fleshed out for a shooter at the time, and while it may seem staid after years of shooters about space marines, I've always had a soft spot for it.
Which is why Sudden Quake grabbed my attention like a Strogg berserker driving its arm-spike through a space marine's chest. It's a mod for the obscure World War 2 RTS Sudden Strike 3, but it replaces all those grey Nazi tanks with the various human and Strogg forces as portrayed in 1997's Quake 2, and Raven's 2005 shooter Quake 4.
Created by modder Kane Peterson, Sudden Quake had its initial release back in February, but has just received a meaty update adding a bunch of new features. "Sudden Strike 3 has no population limit and handles huge amounts of destruction and craters," writes Peterson on the game's ModDB page. "This is carried through into Sudden Quake. This means enormous battles between thousands of marines and monstrous cyborgs, with no limit to the scale of the destruction."
The mod's still in active development, but it already has a fair amount of playable content. Alongside the two campaigns of the original version of the mod, this second version adds five additional custom maps (bringing the total to six), and introduces new units like a marine hovertank. The mod also features a bunch of unique mechanics, like Strogg orbital drops and jet packs for the Marines.
In the responses to the update, Petersen details potential new features for Sudden Quake going forward, including "creating new Strogg types that have never been seen" and "some new settings like the Stroggos moons and a partially-stroggified planet". I mostly mention this so I can write the word "Stroggified", but I also like the idea of expanding the Quake universe beyond Stroggos, something the mainline games didn't do.
You can download Sudden Quake here. Note that you'll need a copy of Sudden Strike 3: Arms for Victory to play. You can grab this over on Steam. Be warned, some of the reviews mention problems getting it to work with the 64 bit version of Windows 10.