I figured I'd make a topic about how this game's rulesets differ from OGL. It can be updated over time to try and be fairly close to comprehensive. This is *NOT* intended as complaints- only as a quick reference for those who are familiar with the D20 system to understand how this ruleset differs, so they can get up-to-speed quickly. Personally, I think most of the limitations were excellent design choices intended to simplify the interface and allow combat to flow at a reasonable pace.
General
* No skills. Concentration checks are based off the caster level
* No encumbrance, only limited number of inventory slots
Classes
* Only Fighter, Cleric, and Wizard available
* No multiclassing, no Prestige Classes
Races
* Only human, half-dwarf, and half-elf are available. Stats differences for them are available during character creation.
Crafting
* Items can be enchanted to a maximum of +10 enchantment, item crafting does not take time.
* Wands and scrolls are cast at full caster level, making them VERY useful
* No staffs. (pointless because of wand/scroll mechanics)
Casters
* Wizards and Clerics cast all of their spells spontaneously. They each "learn" two new spells at every level-up, and can additionally learn spells from scrolls they find or purchase
* Metamagic casting is not a full-round action, only takes an appropriately higher-level spell slot than the original spell. Only one metamagic effect/spell
* No undead turning
* Extremely limited pre-buffing- generally the only spells castable outside combat are "mage armor" and heals.
* Only one AoE effect with a duration on any given tile at a time (no AE silence over webbed area)
Combat mechanics
* No trip mechanics
* No moving through allies spaces during combat
* Crits do not multiply strength/weapon bonus damage - they only roll weapon damage dice again.
* No tumbling
* No combat expertise or Power Attack
* Cover does not prevent AoOs.
Movement
* Player characters cannot move through spaces occupied by other player characters during combat.
Items
* Weapon do not automatically resize. There are two new level 1 wizard spells- enlarge weapon and reduce weapon (both available as scrolls from the first magic shop) which size weapons up and down.
Okay- what did I forget?
Cheers
Ikarius