Castles & Crusades I cannot say enough good things about this game. It has the old D&D feel with some new twists. Castles & Crusades uses the siege engine mechanic which replaces saving throws and skills. Players and GMs can quickly resolve almost any situation using this method. As a result the game plays quick which keep the plot moving.
Character creation is also quick which make this game ideal for a pickup game. But don’t be fooled, Castles & Crusades lends itself seamlessly to extended campaign play. If you still have any of those old AD&D modules lying around you can plug them into the Castles & Crusades system quickly and easily.
Freeform play, while Castles & Crusades does have class abilities there are always some players who want to do more. The siege engine mechanic is an excellent device for creative players to do more than they ever thought they could. For example if a player wanted to hit multiple people in a round the GM need only come up with a difficulty factor and have the character roll for success. In the last game I played at Geneve Con I had a monk who climbed up a troll’s hairy back, grabbed his hopped earring for support, made a called shot to his inner ear, while using my monks stunning fist ability. Because of my miserable dices rolling skill I missed but I was still able to attempt all these actions in one round. While the rules are a simple d20 system they are dynamic and have depth. I highly recommend you pick up this game and try it out.