When I was in Elementary school, we had a small computer lab with about 30 Apple IIe's. Around 4th grade, a large group of us started carrying around floppy disks with various games like Sim Ant, or some cool adventure game I don't remember the name of.

And Bolo

Bolo was an Appletalk tank game, which supported a fair number of players on the same map. Players could ally with each other, build pillboxes/tarmac/walls to defend an area of land, and blow blow each other up a lot. Sadly, it didn't play well with the Appletalk printers, causing print jobs to become lost or truncated. This pissed off a lot of teachers, and eventually they blamed Bolo. The game was banned from the school.

That didn't stop us, obviously. The room was set up in such a way that one computer was on the far side of a low wall, the monitor hidden from view from the rest of the room. He also had decent line-of-sight to spot when a teacher was coming our way. Any time one showed up, everyone but the lookout would quit Bolo and start playing something else. Once the teacher was gone, we'd rejoin the game and (since the map was still active) pick up where we left off.

Once, I got caught :( The teacher made it very clear she was disappointed in me, and made me reformat the disk while she watched. I'm sure she felt the matter was resolved.

Thankfully, she didn't have me reformat the half-dozen other disks with Bolo I had in my bag :D