I was also thinking that a "0-level" game would make a good introduction for new players, and allow them to slowly get used to their characters' abilities. I would split up "0-level" into the "Novice" and "Apprentice" levels, though.
At
Novice level, the idea is to introduce the players to the simplest abilities of their characters and to the basics of gameplay. Novice-level characters have the following abilities:
Hit Points: Constitution+3 for defenders, Constitution+2 for leaders, strikers and controllers.
Healing surges: same as a 1st-level character, but can only be used between fights as Novice-level characters cannot catch a second wind (healing surges don't increase with levels, after all)
Weapon and Armor Proficiencies: same as a 1st-level character (lack of money will be a bigger restriction on choice of weapons and armor for low-level characters, so further restricting proficiencies seems rather pointless)
Class Defence Bonus: same as a 1st-level character (it's a small and constant bonus, and helps to differentiate the characters)
Racial Abilities: All at-will and constant abilities*
Class Abilities: All at-will and constant class features, and one at-will power*
(* Except those related to action points and second wind, which will be introduced in the Apprentice level, along with encounter abilities and powers.)
Trained Skills: All free skills (e.g. Stealth and Thievery for a rogue) and one other.
Novice-level characters do not have action points and cannot catch a second wind.
Novice-level characters become Apprentice-level characters when they have earned one-quarter the XP that a 1st-level character needs to gain a level.
At
Apprentice level, players are introduced to the more tactical aspects of gameplay, including action points, the second wind action, and encounter abilities. Apprentice-level characters gain the following abilities:
Hit Points: +6 hp for defenders, +5 hp for leaders and strikers, and +4 hp for controllers.
Racial Abilities: Gain their remaining racial abilities.
Class Abilities: Gain their remaining class features, another at-will power, and one encounter power.
Trained Skills: Gain an additional trained skill.
Apprentice-level characters become 1st-level characters when they have earned one-half the XP that a 1st-level character needs to gain a level.
At 1st-level, the characters gain their remaining abilities, namely:
Hit Points: +6 hp for defenders, +5 hp for leaders and strikers, and +4 hp for controllers.
Class Abilities: Gain one daily power.
Trained Skills: Gain their remaining trained skills.
Feat: One feat.