I appreciate when leaders do create opportunities for fun stuff. But if you have to stay and work instead of taking a half day if you don't want to attend, what does that say?
That they are worried no one would attend? Check a box that you are trying to “engage” people?
What is the goals of these? Are they forced socialization? A reward? If it's just to be nice, then let people choose home vs the event.
We are asked for ideas, but if I have one, it would be rude to expect some other staff person to organize that (always organized by volunteers).