Desktop Dungeons Kingdom Management is full of mouse-down buttons, which seem counter-intuitive to me and can lead to a user error.
A registered click in many, if not all buttons in the Windows/Mac UI, has two rules, not one:
1. The user presses his finger down while hovering with the cursor above the button (aka mouse-down)
At this moment, when the user moves his cursor while still pressing down on the mouse, the user performs a "drag", for uses most often found in drag and drop actions.
2. The user releases the mouse button while still hovering on the same button (aka mouse-up)
After both 1 and 2 are done, a click is registered by the system.
You may notice two sub-rules, mostly to guide people not used to working with computers imo, but also great for some other situations:
a. There can be many seconds between a mouse-down and mouse-up; holding the mouse down for five full seconds, then releasing it, will also register in a click. Holding the mouse down can be used as a tool of doubt or validation for users in Desktop Dungeons kingdom management. E.g. you hold down the mouse button on the Assassin button, then ask yourself "Do I really want to play as an Assassin? Isn't Rogue a better option for this dungeon?" If not, release the button. If yes, drag away, then click on the Rogue button.
b. A user usually can move a small amount of pixels in either direction (between ~5 and ~12 pixels) before the input is registered as a drag.
This allows for people with not that steady hands, or not have the hand-eye co-ordination that many of us have, to still control the system without much of a problem.
I assume you want to try this yourself, so please go ahead. Look how buttons are reacting when you just do a mouse-down action. And when you do a mouse-up action. And how far you can drag the button before the system registers your action as a drag.
In the desktop dungeons kingdom management, most if not all buttons are registered at mouse-down, not at mouse-up. Strangely enough, the buttons inside the dungeons itself work with a mouse-up click, all feeling much more natural.
It is one of those quirks that feel just off, and might be changed with a simple coding change.
Thanks for your attention.