This well known word came from two different words - old and school, that can have many different meanings when its going together or dispersed.
Actually, it means "oldtimers" (aww...here we go...another term lol), old players, old gamers of the specific game, who have experience, skills, tactics. ATTENTION! Score isnt the most important factor, when we are talking about experience, skills, tactics. Every gamer has his own gaming attitudes, purposes and aims, everybody has an individual way of playing/gaming...and this is it!

OLDSCHOOL is the way of playing/gaming, for example - no teamkill, no spawnkill, no spawncamping, no camping, no sub- and mashineguns, no shooting at players when they are typing, NO INSULTS (alwise polite), no flooding/spamming chat, no teamtazing, no jumping like crazy arroud the area and so on...
However, there are 2 different types of members for this particular school:

1. Old gamers (3-4 years)of the specific game (COD, LOSV) who have specific skills on that game, were playing it since it had showed up for the first time, and know almost everything about it. "They have graduated gamers school of that game long time ago".

2. Gamers, who are not old players of that game and got no bright skills on it, but got attitudes and familiar way of playing/gaming, in this case they also belong to "oldschool" just they need to get more skilled, what isnt too hard when you are already good at an other game.

In this way I am always a member of an oldschool, no matter if I play a game for the first time and my classmates are much more skilled, experienced and older than me.
Hey, its never to late to study! So come on and take a course!