Can I have a button to do stuff and then escape to quit or not?
Can I have a keyboard/mouse button and then a clickable one on screen to change the action or will that be counted as 2 buttons?
For menu you can have different buttons. The 1-button rule only applies to actual gameplay, though it would definitely be an interesting challenge to figure out how to handle menus with the same button :)
As for having a second clickable button, that does count as a second button so it's not quite fitting for the jam. Think of a different way to change the action. Maybe holding the button changes the action? Or double/triple tapping it? Or maybe the action changes contextually. To give you an example, in my game if the character is on the ground the button acts as a jump button, but if the character is in the air it's a fire button.
Having the menu being usable with 1-button is waaaaay better for sure, if you can do it =)
It's very difficult, though, to implement Escape and Pause during the game with one button, so feel free to keep Esc to quit, and something like P for pause or whatever.
The 1-button rule mainly means that :
- you can play the game just by hitting/holding the same key ;
- several keys can be mapped to this unique button for better comfort (space bar, LMB, X on a gamepad... all could trigger the same thing).
As for the onscreen button, well...
There's no mouse mouvement in such games, so a "clickable" button is off topic. But you can have an interface with several buttons. For example, a simple tap on your key moves to the next UI button. Holding the key activates the current UI button, etc.
We usually consider here that mouse movement uses at least 2 buttons already (x-axis, y-axis), so it's beyond the scope of this jam indeed.
But, well, if you have an original idea, you can go for it. It's better to make a game than nothing.
Or can can take part to the sister jam : https://itch.io/jam/2-buttons-jam-2022
In any case, good luck and have fun :)