Distractions

I know I should be doing other things, but I can't get this idea out of my head.
I am making a 4th edition D&D version of Warhammer 40,000.
After looking over the Dungeon Master's Guide last night, I hit on the idea of using a basic racial template for Space Marines, much like you start with a monster's stat block, then add a specialist class to that, as you would when creating a customized monster role, and from there, you just add lots of special equipment, feats and skill selections.
Very simple really.
Since the characters will be quite basic, with only a few special abilities, they will be less exciting to play all the time, so I am going to have a platoon list available, of many characters, and the players get to build a squad at the mission briefing stage, where they pick a character from the platoon list that they are going to play, also, if the character gets incapacitated, they can call in fresh troops to replace those that are lost.
The basic Space Marine is modified slightly by his Background, which is his planet of origin, and this may influence his skills, base stats, feats and possibly his potential for psionic talent (Psiker abilities)... I am toying with the idea of Psiker ability being a risky thing, with potential for mutation and corruption.
Generally, the missions will reward troops with experience, chapter honors and relics.. the relic items are more powerful equipment for the troops.
The main equipment focus will be the Power Armor all marines except the Scouts wear, followed by the main weapon (typically a Bolt Rifle, or Bolt Pistol and Chain-sword) and then specialist equipment, such as Heavy Weapons, Sniper Rifles, Explosives, Targeters, Remote Weapons, and the all important Stim Packs.
Stim Packs will take the place of Healing Surges, and due to the more lethal nature of this game, the players will be able to pop Stim Packs as a Minor Action, whenever required (however, they don't get the total defence bonus of a Second Wind).
Each character will start off with a set number of Stim Packs on each mission, and there will be special items and chapter honors which award higher numbers of base hit points, later in the game.
Levels are important, because they allow access to high level equipment and make new class options available, such as the all important Apothecary, Force Commander, Librarian, Inquisator, Techpriest, etc.
Of course, there is a huge amount of information to draw on as I go, thanks to the very creative fans who have compiled a thorough wiki on the 40K game setting.