According to my blurry memories, the movie starts with a (new?) kid in a college, where there are strict rules and even stricter internal hierarchy, and this kid had some issues fitting in. Perhaps he had issues back at home or there is war going on in the world outside the disciplined insitute’s walls, I can’t recall. The only image I remember is that these kids play a kind of ruthless strategic game in the college’s garden (or nearby forest?) at winter time. This is organized by the school and everyone participates, but of course theachers do not always know what dirty tricks go on in the woods. The game is a kind of numbers’ war where there are two parties fighting: they have to read out numbers attached to foreheads of the members of the other party to make casualties. To survive, you have to hide or shield your number against others to read it. Elder kids are quite good and ruthless in this and some use (illegal?) instruments like smoke bombs or mirrors to help themselves.
I’ve seen this movie in the 80-s (or early 90-s?) in television in Hungary (or in the movies?). I think it was a British college (certainly had the look and feel of it), but don’t take it granted. Since this war of numbers game is not very widespread outside of Eastern Europe, it might not be a British (or US) film at all. Considering how many such movies we had in the Eastern block at that time, it could have been anything, even Checkoslovakian.