Now I'm a big fan of simple, free and old school RPG. I came across the Castles and Crusades RPG in my quest for free gaming, now this isn't a free system, but it does have a free downloadable quick start rules, plus there are plenty of freebies out there on the net for this system.

http://www.trolllord.com/cnc/ccqs.html
www.dragonsfoot.org/cc/

The reason why I've picked up on this system as a freebie is because its based on old school mechanics, and its been designed so that its compatiable with D20 based systems and old D&D system, though a system of easy conversion. This means that all those old D20 or D&D, AD&D books laying around gathering dust can be pulled out from under where ever they've been stuffed for the last ex amount of years and put to good use again.

This system is a gem, you can use thier core mechanics and pulled rules from other systems that you like to use within the game. This game has a combat system remissant of the old D&D combat, its fast, easy to uderstand and makes the game much more enjoyable to play, no more rumaging around looking at stat blocks trying to work out the complicated math and getting bog down in the rules.

While much of C&C brings back feelings of classic D&D, they've also pulled in a ton of stuff from newer versions. Each class in C&C has a primary attribute, and those match well to the primary attributes from 3.5, so someone familiar with more recent versions of D&D will feel at home.

Primary attributes are far more critical in C&C, though. Each class has one primary attribute. Each non-human character can have a total of two primary attributes (called Prime attributes), so you can pick your second Prime attribute based on how you want to play your character.
So if you're a Paladin, your class' Prime is charisma. If you want to play your Paladin as a butt-kicking holy warrior, you would probably choose strength as your second Prime. But if you plan to play a rogue type of Paladin, you might choose dexterity as your second Prime. The older wise holy man would choose wisdom.

Prime attributes will have a direct effect on what your character is good at, which is why they're a key point in character creation. Human characters get a total of three Prime attributes, to make up for the fact that they don't get much in the way of special abilities.
These are a great set of rules, and if you do decide to start playing I would recommend that you eventually invest in a copy of the Players Handbook, as this will be the only book you'll need. You will find on the link above to Dragonsfeet a ton of free usual bits and bobs for C&C, plus there is an absolute plethora of material for D&D and AD&D on the site as well which you could also utilise.

A PDF version of the Players Handbook can be purchased from RPGNow.com for $14.99
http://www.rpgnow.com/product_info.p...=0_0_0_10126_0

I've included an extract from the following blog about converting old material for use in C&C;
http://dnd-realm.blogspot.com/2010/0...-crusades.html

Converting from D&D/D&D.

Armour Classes.
To convert a D&D Armour Class to C&C, simply subtract the given AC from 19. Remember that subtracting a negative number equates to the same thing as addition.

So a D&D monster listed as AC 5 would be AC 14 in C&C (19-5= 14). A monster with AC -3 would become AC 22 in C&C (19+3 =22). Saves are easier to convert. If the creature saves as a fighter, thief, dwarf, or halfling it is Physical prime. If it saves as an elf, cleric, or wizard it is mental prime. Use the creatures HD as the bonus to all rolls (including saves, attacks, etc).

If using 1st or 2nd Edition AD&D as a resource, Armour Class is also easy to manage. Simply subtract the listed AC from 20. So an AC 5 creature would be AC 15 in C&C and an AC -3 character would be AC 23 in C&C.

Converting Save Throws

Older editions of D&D had 5 saving throws. C&C has 6 and they are roughly the same, except the C&C saves are directly linked to stats. The old D&D saves were as follows and converts to C&C as presented below:

Saves vs. Paralysis – Castles & Crusades Strength Based Saves
Saves vs. Breath Weapon (and area of affect spells like fireball) – Castles & Crusades Dexterity Based Saves
Saves vs. Poison, Death – Castles & Crusades Constitution Based Saves
Saves vs. Wands, Staves, Wands (and Illusions) – Castles & Crusades Intelligence Based Saves
Saves vs. Spells (except illusions and area of affect spells like fireball and charm or sleep spells) – Castles & Crusades Wisdom Based Saves
Saves vs. Enchantment spells (sleep, charm, etc) and fear – Castles & Crusades Charisma Based Saves

Converting damage from Traps.

If the Traps Damage is related to a spell, look up the C&C equivalent and adjust the effect accordingly.

If the Traps Damage is related to a weapon, look up that weapons damage in C&C and convert it.
If damage is listed as a die with a damage bonus exceeding the die types, add another die to the damage instead. If it has a damage bonus less than the die type, get rid of the bonus damage.

So if a trap is listed as doing 5d6+7 damage, convert it to 6d6 damage for C&C. If it does 5d6+4 damage, its damage is just does 5d6.