I've been tracking this for a while, and it just launched into early access on Steam. Very positive feedback from people who've had beta keys, and I just picked it up myself.
Here's the gist: It's a single-player only RTS oriented around building a steampunk-flavored colony in the post-zombie wastelands. The primary mode, and the only one available right now, is a timer-based survival deal where you're aiming to last for a certain amount of time against increasingly heavy waves of zombies, both spawned on timers and random hordes formed from the passive mobs of them on the map.
It's all sounding pretty generic, I'd bet. The hook is that the resource management is complex but clear, and really tightly wound. You're going to be spending every minute scrambling to macro as efficiently as possible while also juggling micro for the forces you're using to clear out new land, build up passive defenses, and save up for research. Even the default difficulty on the easiest map feels really damn tense. Speaking of difficulty, there are two adjustable settings: duration, and enemy density. The latter is obvious. The former scales difficulty
up as the time you have to hold out for is lowered, because it's compressing the attacks that normally occur over 100 days ingame down to 80 or 60 or whatever. That, and there's no reloading saves. When your colony falls, your save gets deleted.
There's lots of well-planned little points. Walls are strong, but you can only build them two-thick. Units can't pass through buildings--if you turn your colony into a messy underhive dealie, your soldiers are going to get stuck walking single-file through crooked alleyways trying to get to the walls before they're breached. If you use soldiers armed with guns, they attract more zombies than your archer scouts. Whenever zombies infest a building that supplies population or workers, all of the people based in that building burst out as new zombies for the horde, making any breach that reaches your residential districts a likely game over. Most to the point, they're not kidding about the name: the devs have the engine set to support ~20,000 units onscreen at once. If you don't clear all of the passive zombies from the map, the last wave of the game will drag them all in on the final assault.
You unlock new maps by beating earlier ones at given difficulty levels. The maps are generated with a set of general characteristics and visuals unique to each-ferex the first map will always generate with a lot of natural chokepoints between forests, mountains, and lakes (all of which are impassable terrain), since it's the first map and they wanted it to always be a bit easier. They've got a full campaign slated for launch in early 2018. The game's $25 US, on a small 10% sale for a week or so for launch, and IMO well worth it even with only the survival mode. The music and sound are pretty good, the art style is tasteful, the gameplay feels solid.
HERE is the official trailer.
HERE is a screenshot they've had up that might give you a decent idea of what you're looking at on higher difficulties if you're sloppy.
HERE is the last bit of a 180% difficulty match on the first map played by one of the youtubers I watched before buying. FWIW earlier in the stream he mentioned being a Diamond league Starcraft II player. The other folks I watched didn't have as much RTS experience and got shitstomped even on 100% difficulty.