Microlite20, including expert rules and plenty of house rules. I’ll be guiding the whole thing so don’t worry too much if you don’t understand the whole lot straight away, I’ll help you sort it all out. There’s a nice compendium of m20 rules and extensions that people have come up with, available at http://dl.dropbox.com/u/11928/Microlite20-RPG-Collection-Spring-2010-Revised.pdf
Background info / character creation guidelines
In terms of backstory, I’d like it if you all come from the same town and know each other reasonably well. You’re all fairly young, probably just out of school and starting apprenticeships in various skills – magic, divinity, fighting, etc.. basically you’re apprentices of whatever class you choose. I’m happy for people to play as classes from the expert rules section like druids, rangers, illusionists, etc
The magic system I’ve ended up deciding on is the Vancian magic system which is somewhere around page 30-35 in the pdf I think. It’s basically like the D&D 3.5 system where you don’t use any mana or hitpoints to cast spells, but you have a limited number of spells that you can prepare in a day, so a level 1 mage can prepare and use one level 1 spell a day, and as many level 0 spells (cantrips) as they want. But I’m going to make a slight modification because the d&d 3.5 magic system fucking sucks at level 1 since mages are almost totally useless in a combat situation. So I’m going to add a little feature where pure casting classes like mages and illusionists are allow a single level 1 attack spell as a free spell that they can use at will, like magic missile, which is an at-will power in D&D4E. Because I’m a nice guy. Of course, it will be a Magic attack, with corresponding magic attack roll and bonus. But, you know, close enough.