Javascript Checkbox and Radiobutton Abilites combined

long time user, first time poster.

I've come accross a very distinct problem, maybe one of you can help me.

I need to built a control form with checkboxes; as soon as one user clicks one checkbox the other, already checked, boxes should be unchecked (like radiobuttons).

Now the problem: The user also should be able to select / check multiple checkboxes (eg. in the windows file explorer STRG + click).

My first instinct was to solve this problem with jQuery, but my solution was not very elegant and hardly working.

Does anyone have any better ideas, more elegant solutions?

best regards, Paul.