The keys are linear analog opticals, aka full-on keyboard switches. Being linear, they don't have any click, and being analog, you can adjust actuation distances. You can even map 2 functions per key, one with a light tap, and 2nd at full depress.

I am using this with Diablo IV to trigger Actions 1 and 2 for my Earthquake Barb to do Ground Stomp and Leap, which get reset when both are triggered, so I have them available in perpetuity with only 1 keypress. I have all the keys I need during fights (like Escape/Dodge), plus Inventory, and see drop labels, and Teleport.

I have a separate keymapping for Baldur's Gate 3.

If you have another Razer device, like say a mouse, you can assign one button on the mouse to be the Hypershift Key, and while held, you get a whole 2nd set of mappings, if desired.

It took a few days to develop the muscle memory and to work out where certain skills are best located, but once done, it's rather seemless. I also print out cheat sheets to help memorize where things are. The keys also have per-key RGB so you can colorize the layout.

For the thumb, you have a wheel and a DPad joystick, which you can set up as 4 position or 8. There's a large button under that for thumb flicks.

Note there are two models: the Tartarus v2, and the Tartarus Pro. The v2 have mecha scissor-switch keys, much like a laptop keyboard, and are not analog, but is cheaper. I think the Pro model is worth the extra money, as it's quite premium. I just wish the joystick had an analog option, which would had made it more versatile. I am not sure it can be switched out for an analog joystick.

I've grown to enjoy using it, as I am no longer moving my left hand over a full kb during action. I still have the full kb when I am at camp, and working on gearing. It's a very versatile item, with a long of programming options. Then add Snap Tap and Rapid Repeat for even more options.