If you don't know anything about it, the team has put together this handy little video:

We wrote about the crowdfunding campaign when it began, but just in the past week we've learned that Apertus will be offering an additional sensor option, a 2/3" inch 1080p sensor which is very close to Super 16mm, and Monochrome versions of all of the sensors currently available (2/3"/Super 16mm, Micro 4/3, and Super 35mm):

Apertus Axiom Available Color and Monochrome Sensors and Prices

Not only that, but the project will be receiving the support of the Magic Lantern team. This is huge news, as they have done some amazing work with Canon cameras (and will continue to work on them), and they will likely be able to do far more with Axiom as they'll have full access to all of the source code. A1ex from ML has said that depending on how the Super 35mm 4K sensor is sampled, it may be capable of a whopping 800fps in 1080p mode, which would be incredible (though this wouldn't necessarily be something available in the first iteration of the camera as it's limited by its outputs at the moment). Check out some of his detailed calculations here, where he mentions:

Global shutter and 300fps are not free - you lose a little low light ability, but not much.
CMV12000 - full resolution
The base ISO is about 400 (maybe lower once you attach the IR blocking filter), and it goes to about ISO 1250 with analog amplification. At high ISO, the noise improves by only 0.4 stops. If my math (and also DxO and sensorgen's math) is not screwed up, this sensor is on par with the little Nikon 1 V2, and about 1 stop behind a Canon 60D.
The row noise (banding) is a major problem, and I don't currently have a solution for it.
CMV12000 - 1080p
I didn't test this mode, but with proper 2x2 binning (without introducing additional noise), this sensor would catch up (but that's because Canon does poor downsizing). At its base ISO, it's really close to the 5D3 in 1080p RAW at ISO 800 (note that 5D3 ISO 800 in LiveView is more like DxO ISO 500). In low light, it's only 0.5 stops behind the 60D in 1080p RAW (1734x975), and about 2 stops behind 5D3 in 1080p RAW ISO 6400.
Not bad for a very fast sensor with global shutter. And there are tricks to squeeze even more DR, without motion artifacts, like averaging 4 or 6 frames, or exploiting the black sun correction to squeeze more highlights.
For low light, in rolling shutter mode, the smaller sensor is better on paper, despite its smaller size (I expect it to be about 1 stop better). I didn't test this sensor, so I've only plotted what I could figure out from the spec - but there are hints that low-light performance might be even better.
I believe this sensor will be very similar to GH4 in low light, and with a bit of luck, on par with 60D (which is 0.5-stop better than GH4).
In global shutter mode it's not that good for low light - you'll get better results from a smartphone (Lumia 1020).
But hey - you can choose between global shutter and low light, without swapping the sensor!

Apertus Axiom Size Comparison

Though the Super 35mm sensor dynamic range may not be that high, there are some interesting on-the-fly HDR modes that could be useful in higher-contrast situations:

Here's the previously published test footage:

And here's a new grade of some of the test footage by Kimon Kodossis that was shot by the Apertus team:

There is still time to get in on the crowdfunding campaign if you'd like, and if you back now, you'll have an upgrade path to the production version of the camera they are calling Apertus Axiom Gamma:

Apertus Axiom Development Cycle

They also have some interesting stretch goals:

€110,000 - AXIOM Beta Remote Control with Real Buttons and Knobs: We will develop an AXIOM Beta wired remote control device complete with LCD, buttons, knobs and dials (no live video monitoring). A wireless design might be possible, but needs more testing. Estimated retail price of the Dictator will be around €300 (gross estimate)

€120,000 - Active Canon EF Mount: We will develop an AXIOM Beta EF lens mount module with electronic lens control. This will allow setting aperture and focus (with the Dictator or from a smartphone/tablet) with most Canon EF lenses when attached to the AXIOM Beta. Canon EF Mount retail price will be around €300 (gross estimate)

€130,000 - AXIOM Beta Active Battery Mount: We will develop a battery mount for NP-F970/F750/F550 batteries to power the AXIOM Beta. Includes power usage and capacity monitoring to estimate remaining charge and time remaining.

Apertus Axiom Battery Prototype

There will certainly be more interesting updates in the future for this project, and you can check out their website for all of them.

Source: Apertus Axiom Indiegogo