So, perhaps I should outline why I really enjoy "old school" gaming. This is not to say that I don't enjoy modern games or that older games are in any way superior. It's just me thoughts.
1. Quick and easy to learn, yet easily expandable.
Games like Basic D&D, Labyrinth Lord, Swords and Wizardry and Basic Fantasy Roleplaying can be learned by the players in just s few minutes and by the GM in just a few hours, yet they are easily modfiable in many ways. Want critical hit carts? Grab your old ones from Rolemaster. New races can be borrowed from anywhere, especially versions of D&D. These games expect and really encourage the players to make them their own.
2. Quick character creation. Roll stats, pick a class, roll hit points, buy equipment and go. These types of games are great for when you want to just sit down and play and don't want your first session to be dedicated to just making characters. This also comes in handy when characters die. Yes, I said die. We'll talk more about death later on but for now suffice it to says that when a character in one of these games dies, there is no need for the character to be out of the action for a long time. Just follow the steps above and voila! Grob the Dwarf part II.
3. Character die. They die and the do it a lot. I'm sure that you are thinking, "ooooh, GM with an attitude here." No, not really. The threat of death was something in old RPGs that I found very exciting, even as a player. I never wanted my character to die, but I was an adventurer by the gods! I needed to do dangerous things and there was nothing like saving vs a deadly poison, or trying to avoid the basilisk's petrifying gaze, to get the blood flowing. It conveyed a sense that was we were doing was inherently dangerous in the world that our characters occupied. The rule of these old games usually made certain to stress that there were no winners of losers in RPG. Among the players that is true. Among the characters it is another story. No, no matter how generous would say that Grob the Dwarf had "won" when he got swallowed by the purple worm and subsequently was digested in its foul gullet. Grob had lost. He has lost his very existence, barring resurrection or wishes, which tended to be rather rare in older games. Grob's player had lost a character, but he didn't lose the game. He could quickly roll up Grob II or Grob's younger brother Grib, the party would run into him around the next corner and off they would go. Even better, Grob's player could take one of Grob's reatiners as his new PC and never miss a beat, except for perhaps the time taken to divy up Grobs loot. Waste not...
These are just a few thoughts that I've been having. There are more, but it is late, so perhaps I will continue this another day.