The Unicomp Ultra Classic is a clone of the classic IBM Model M, the “clicky” keyboard. It’s like the polar opposite of the scissor switch, but included here because sensitive typists also favor this type of keyboard.
The feel of the Model M was based on the IBM Selectric, which was once the dominant typewriter in offices, globally.
These use the IBM buckling spring design of the Model M. These are springs attached to a little paddle; when you press a key, the spring eventually buckles, and the paddle flips down, pressing the membrane switch. When the spring buckles, it make the clicky noise, and the resistance in the key changes.
So, as you got used to the keyboard, you would stop pressing the keys all the way to the bottom; instead, you’d push through the resistance, effecting the switch, and then move your finger off.
(This is probably why people who like the laptop keyboards also, often, favor the IBM keyboard. The laptop keyboard’s travel is so short, from 1mm to 2.5mm, that you can move your finger off the key right after resistance is broken.)
If you want to learn more about the classic IBM keyboards, watch this video.