The Fate of the Task Master
The first and foremost rule is to have fun.
Everything else beyond that is trivial
This game follows the 3rd edition rules for Dungeons and Dragons. However, it can be (and in many cases is) modified for 3.5 and Pathfinder rules. The mechanics themselves are meant to be played in a hypothetical sense, so the rolls and actual skills need only to apply to the most general interpretations of the situations. It is more about the meta-game thinking than the actual rolling.
That being said; this will be a difficult campaign. Expect to have your wits tested as well as your flair for strategy. There are a couple of mechanical rules, but they are merely in place to balance classes. You are welcome to play without them, though I highly recommend not to.
1) Recharging Spells.
Replace the term “Spells per Day” with the term “Spell Slots” and you pretty much understand how this will work. Spell slots function like spells per day, however they recharge at a rate of 1d4+spell level rounds per slot used. Spells are assigned normally per class (so wizards must decide ahead of time which slots to fill).
Instead of trying to guess and check, counter-spells function as this. Character sacrifices a spell in a slot (any they choose) and roll d20+Level of Spell sacrificed + Spell Craft. Opposing spell caster must make a spell craft check. If the character wins, the spell is neutralized. If the opposing spell caster wins, the spell functions normally. The character casting the counter spell must have been holding their actions or fighting defensively to attempt a counter spell.
3) Turning Undead.
Turning rules for DnD are (I feel) needlessly complex, especially for a class dependent skill. To turn undead, roll d20 + Class level + Charisma bonus. That number is the number of Hit Die (or levels) of undead creatures you can effect. Now you choose whether or not they receive 2d8+Cha damage or flee for 10 rounds.
For the most part, items are found or given by the DM. No characters start off with any gold or times (what they have they will lose anyway). Class specific items (such as musical instruments, spell books and thieves tools) are also given by the DM but their type and content are amenable for player preference.
For the most part, alignments in this universe are fluid and action based. Paladins are good, or good-ish, but do not need to be strictly Lawful Good. Conversely, Assassins do not need to be specifically evil. Monks, Druids etc should play as close to their class specific alignments as possible, but they are not required to do so.
6) Forbidden Stuff
There are certain spells and items which break the game. Since, at every level you will be leveling up, you will run across the opportunity to craft or acquire such spells and items, you will have access to them, it is important to know that some of these things will not be available and will be forbidden. After all, the Task Master wishes for you to see a true challenge in his twisted game.
Forbidden Stuff includes, but is not limited to: Wish spells.