Warhammer 25K Core Rules 
The game is turn-based, just like 40K. Each model has a stat line, just like 40K. It looks like this, just like 40K: :)

M WS BS S T W I A Ld
4  3  3 3 3 1 3 1  7
And yes, that is the stat line for a basic human soldier. Just like... &ltclick-click... BANG!>
The turn is split into 4 phases, just like 40K except without the psychics (which I don't like much, and will need major playtesting). In order, these are, surprisingly enough:
1. The running like your ass is on fire phase (a.k.a. movement phase)
2. The blowing things into lots of little pieces with big guns phase (a.k.a. shooting phase)
3. The smacking the hell out of things with large blunt and heavy objects phase (a.k.a. close combat phase)
4. The trying to stop running like your ass is on fire phase (a.k.a. rallying phase)
Unfortunately, due to length, I'll be using the alternative names.
Movement phase:
As per 40K, models can stand still, walk, run, hide and set overwatch. However, some of the rules for each move type are different.
The movement phase is split into several steps:
1. Declare charges
2. Move all chargers
3. Move all compulsory movers
4. Move all other movers
Note that all charge moves must be made as declared, straight at the target. This is important, because it is possible for a flamer on overwatch to leave it's template in place, and all other chargers have to move into the flame. Such are the dangers of running headfirst at a man with a flamethrower. You may have a squad charge from inside a vehicle they are being transported in, and in this case may move the vehicle before the squad charges from it.
Squad coherency in 25K is 4" unlike in 40K, to represent the comparatively disorganised state of most fighters, and the informal command structure among the more organised. You may also have members of a squad move as individuals e.g. some setting overwatch, some charging, some moving into firing positions.
Models may intenionally pin themselves at the start of the movement phase. You may also deploy your models pinned at the start of the game.
Finally, any model that is pinned (see below) can only move two inches. If a pinned model moves, it may not shoot that turn.
Shooting phase:
Once again, rules are similar. Here are the changes:
1. Cover works differently. Decide what hit modifier is used based on how much of a model is obscured. If it's more than half then the modifier's -2, less and it's -1. Decide whether the cover the model is in is 'soft' or 'hard', using the same rules that 40K uses. Weapons with any kind of template or blast marker ignore soft cover. 

2. If a model doesn't shoot in his own turn despite having the oppurtunity, he may shoot at the first moving target within short range during the opponent's movement phase (i.e. the first charger, or someone moving out of cover to shoot, but not a line of men moving in the distance), or at the nearest target at the end of the opponent's movement phase. This is termed oppurtunity fire, and is at -1 to hit. You cannot throw grenades on oppurtunity fire, or fire a jammed weapon that you cleared in the previous shooting phase.

3. Models setting overwatch may shoot before, during or just after any enemy movement, or at any target they wish at the start of one of the opponent's movement phases (this means that overwatch can be used to ignore the ordinary targetting rules). Models on overwatch may throw grenades.

4. Throwing grenades at a specific point is at -2 to hit. However, if you are trying to catch several members of a squad in a blast, you may add +1 to hit for every 1/2" of blast radius that isn't needed to catch the intended target. For example, if a soldier throws a frag grenade (2" blast) at two soldiers standing 1/2" apart, only 1" of the blast is needed to hit the pair, giving a wide margin of error and therefore +2 to hit.

5. Sustained fire weapons may fire on 'full auto'. On full auto, you roll your sustained fire dice first and then roll to hit for each hit generated by the sustained fire dice. However, these shots are at -1 to hit, to represent the difficulty of aiming a long drawn out burst accurately enough to score full hits.

5. If a standing squad or model is shot at, he/it becomes pinned. This represents troops diving into cover or to the ground. Place the model(s) lying down. Pinned models can either move 2" or shoot, but are harder to hit. Any model or squad becoming pinned may make a leadership test to avoid it, choosing to charge bravely, or maybe suicidally, into enemy fire.

6. Shooting must be done a squad at a time. Therefore, pinning is worked out after one squad fires and before the next, affecting the next squad's to hit rolls. Targetting works like 40K, so everything except special and/or heavy weapons within a squad would normally be shooting at the same target.
Here's the table of to-hit modifiers:

-1    Vehicles at fast speed
-1    Shooting at a fast moving target (10-20")
-2    Shooting at a very fast moving target (>20")
-1    Target partially (

Warhammer 25K Wargear List 
See 40K wargear book.
Flamers:
If a model armed with a flamer stands still, it may choose one of the following attacks:
Continuous Flame: The model holds down the trigger on the flamer for a protracted burst of flame. The flamer template stays in place until the start of the opponent's turn. This may be used on overwatch.
Sweeping Attack: The model sweeps the flamer across an arc, toasting a large number of nearby troops. Place the flamer template at the start of the arc, and spin round until the end. All models covered by the template as it moves are hit. This may *not* be used on overwatch.
Sniper Rifle:
In an age in which the needle sniper rifle was impossible to find ammo for at best, and impossible to find working at all in most places, snipers had to resort to large-calibre rifles instead. These weapons are often large and difficult to handle, but are easily capable of killing with a single shot. 

		Shooting to hit
Short    Long                                       Save 
range:  range:   long:   short:  Strength:  Damage:  mod:  Special:
12"      24"      -       +1        5         D3     -2    -2 to hit if you move and fire
Bolters:
Bolters no longer get the +1 to hit at close range, due to early technology.
Grenade launchers:
Grenade launchers now have a 24" long range and a 12" short range. They no longer have the move or fire restriction.
Mortars:
These are support weapons and must be used by two-man teams. Mortars may indirect fire at a -1 to hit penalty, but at least one model must be able to see or detect the target. When you fire it, roll the artillery dice. If a mortar hits it's target, then it scatters D3 inches, otherwise it scatters using the artillery dice roll. All the usual explosion rules apply.
When shooting at the weapons team, there is a 50% chance of hitting the mortar at long range (roll a D6, 4+ means you hit the mortar), or you can choose to hit either the crew or the weapon at short range. The mortar has an armour value of 13, and is destroyed if it's armour is penetrated. If one of the crew is killed, the weapon may only fire every other turn, due to time spent reloading.
		Shooting to hit
Short    Long                                       Save 
range:  range:   long:   short:  Strength:  Damage:  mod:  Special:
24"      96"      -1       -        4         1      -1    Move or fire, 2" blast radius
Spider support turret:
The Spider is the precursor of the Tarantula. It needs a two-man team to operate, and carries either a twin-linked heavy stubber or a twin-linked heavy bolter. Anyone targetting the crew has a 50% chance of hitting the spider at long range, or may choose their target at short range. If one of the crew members is killed, the spider may only fire every other turn. The spider itself has an AV of 13, and is destroyed if penetrated.
Devastator Anti Air/armor Cannon:
The Devastator AAC is a support weapon consisting of a quad-linked autocannon mounted on a wheeled chassis. It is designed to destroy aircraft and vehicles, and while the cannon is very slow to move around, it is capable of laying down a devastating hail of fire that can kill whole squads of men or lay waste to battle tanks. 
Once again, targetting the crew at long range leads to a chance of hitting the devastator, in this case, 66% (3+ on a D6). The devastator has an armour rating of 16 to represent extra layers of armour built into the chassis. If this armour is penetrated, the devastator is destroyed.
If one of the devastator's crew is shot, then only two of the auto-cannon will be loaded each turn. This means that you can fire two sustained fire dice off each turn, or wait a turn and fire a four sustained fire dice burst. If both loaders are killed, the gunner is forced to handle reloading, which means that you can fire two sustained fire dice every other turn, or spend two turns loading and fire a four sustained fire dice burst.
Due to special ammo feeds, the devastator may re-roll the first jam each turn. Due to it's weight, the Devastator may only be moved 4" in a turn.
		Shooting to hit
Short    Long                                       Save 
range:  range:   long:   short:  Strength:  Damage:  mod:  Special:
20"      72"       -       -        8         D10     -4    Move or fire, ignore first jam
Conversion Beamer:
Use the 40K rules for now... half rate of fire if one crewman killed, AV 13, destroyed if penetrated.
Flak Armour:
The usual 6+ save with +1 for being stuck in a blast
Combat Armour:
5+ save. This is the predecessor of power armour.
Wargear Cards:
The following wargear cards work exactly the same as in 40K:
Armour-piercing ammo
Seeking Ammo
Auxiliary grenade launcher
Chameleoline
Frenzon
Medikit
Targeter
Bionic Eye
Bionic Arm
Bionic Leg
Scanner
Digital Lasers
Along with these, here are some additional cards for 25K:
Proto-type Power Armour: 7 points
4+ save, sealed suit. For an extra 3 points, comes with concealed weaponry (see wargear card).
Tech's tools: 10 points 
Give a non-tech the ability to fix vehicles like a tech. If given to a tech, he may use this table for fixing vehicles:

4-6 Perfect repair! The damage is fixed.
3   This could take a little time... the damage will take another turn to fix. Next turn, roll a D6. On a 3+, the damage is repaired, otherwise it's irrepairable.
1-2 FUBARed. The vehicle's had it.
Suspensors: 5 points
Allow the wearer to move and fire a move-or-fire weapon.
Silencer: 5 points
May be fitted to an autogun or sniper rifle. The model may fire the weapon while hiding without revealing itself.
Concealed weaponry: 3 points
The character has numerous weapons secreted around his/her body, possibly including retractable boot blades, a knife up his/her sleeve and so on. As a result, any drawn combats are won by this character, and if he/she loses a round of combat, then if the character is still alive after the winner's hits have been applied, the opponent takes a hit, using the character's strength.
Melta-gun: 10 points
As per the ordinary weapon
Plasma gun: 10 points
As per ordinary weapon
Mk.1 Plasma gun: 10 points
As per Chaos weapon
Plasma pistol: 10 points
Like the ordinary gun
Mk.1 Plasma pistol: 10 points
Like the ordinary chaos weapon
Melta-bombs: 7 points
Gives the owner of the card a supply of melta-bombs
Hallucinogen grenades: 5 points
See wargear book
Choke grenades: 4 points
See wargear book
Scare grenades: 5 points
See wargear book
Blind grenades: 3 points
See wargear book
Power fist: 12 points
See wargear book
Power Axe: 9 points
See wargear book
Power Sword: 8 points
See wargear book
Hand Flamer: 7 points
Have you spotted the pattern yet?

Warhammer 25K Human Army List 
This is a basic army list for humans fighting around the ruins of Earth. 
At the moment, playable armies are probably somewhere between 200 and 500 points. The first game I played was 300 points, and was probably equivalent to a 1500 point battle, although it passed quicker than usual, which I would like to believe was due to different game mechanics and simpler army lists.
Wargear:

Basic weapons:

autogun         1 point

lasgun          1 point

boltgun         4 points

shotgun         1 point

assault weapons:

stub gun        1/2 point

autopistol      1 point

laspistol       1 point

bolt pistol     3 points

sword           1 point

chainsword      2 points

2-handed weapon 2 points

grenades:

frag grenades:  2 points

krak grenades:  3 points

smoke grenades: 2 points

special weapons:

grenade launcher: 5 points plus grenades

flamer:           10 points

sniper rifle:     6 points

heavy weapons:

Heavy Stubber:  10 points

Heavy Bolter:   20 points (these things are rare+v.powerful against T3)

Autocannon:     15 points

Lascannon:      40 points

Missile Launcher: 30 points (dual purpose...)

armour:

flak armour:    1 point

combat armour:  4 points

Army list:
Characters:
up to 25% of your army

0-1 Captain 40 points
M WS BS S T W I A Ld

4  5  5 4 4 2 5 3  9

weapons: none
The Captain may choose wargear from the basic, special, assault, grenades and armour sections of the wargear list.
He may also carry up to three wargear cards (NOTE: the ordinary 40K wargear cards may not be used).
May lead your army. Has a strategy rating of three. May ride a vehicle purchased from the vehicles section, in which case he either becomes a passenger or replaces a member of the crew.

0-1 General 40 points
M WS BS S T W I A Ld

4  3  3 3 3 1 3 1  7

weapons: none
The General may choose wargear from the basic, special, assault, grenades and armour sections of the wargear list.
He may also carry up to two wargear cards.
May lead your army. Has a strategy rating of four. May ride a vehicle purchased from the vehicles section, in which case he either becomes a passenger or replaces a member of the crew.

Medic 25 points
M WS BS S T W I A Ld

4  4  4 4 3 1 3 1  8

weapons/wargear: Medikit
The Medic may use weapons chosen from the basic, assault and grenades sections of the wargear lists, and the armour of your choice.

Sniper 20 points
M WS BS S T W I A Ld

4  3  4 3 3 1 4 1  8

weapons/wargear: Sniper Rifle
The sniper must start the game as a member of one of your squads. He may be armed with extra weapons chosen from the assault and grenades sections of the wargear list, and armour from the armour list.
You may give the sniper one wargear card.
If the sniper does not move for a turn (he may set overwatch), he may shoot a particular member of an enemy squad instead of randomising. This allows him to intentionally pick off a heavy weapon, for example.

Tech 20 points
M WS BS S T W I A Ld

4  3  4 3 3 1 4 1  8

weapons/wargear: none
The tech may be brought weapons and wargear chosen from any section of the wargear list.
He may also be given up to 3 wargear cards, and ride in a vehicle brought from the vehicles section, in which case he either becomes a passenger or replaces one of the crew.
A tech may attempt to fix a damaged vehicle. Roll a D6 and consult this table:
5-6     Perfect repair! The damage is fixed.

3-4     This could take some time... the damage will take another turn to fix. On that turn, roll a D6. On a 4+, the damage is repaired, otherwise it's beyond fixing.

1-2     FUBARed. The vehicle is well and truly stuffed up, and will take several weeks in a fully equipped workshop to fix... if you're lucky.

Veteran 10 points
M WS BS S T W I A Ld

4  4  4 3 3 1 4 1  8

weapons: none
You may buy a veteran wargear chosen from any section of the wargear list.
You may also buy the veteran a wargear card.
A veteran may lead a squad, in which case he is a part of that squad and cannot leave.

Squads:
Minimum of 25% of your army

Assault-type squad: 5 points each
M WS BS S T W I A Ld
4  3  3 3 3 1 3 1  7
weapons: none
You may buy each model any weapons and wargear from the assault, grenades and armour sections of the wargear list. Up to two models may carry a special or basic weapon. 

Tactical-type squad: 5 points each
M WS BS S T W I A Ld
4  3  3 3 3 1 3 1  7
weapons: none
You may buy each model one weapon from the basic weapons list, one weapon chosen from the assault weapons list and any number of grenades from the grenades list. Up to two models may replace their basic weapon with a special or heavy weapon. All models may buy armour from the armour list.

Devastator-type squad: 5 points each
M WS BS S T W I A Ld
4  3  3 3 3 1 3 1  7
You may buy each model one basic, special or heavy weapon, plus one assault weapon as a side-arm. Models armed with a grenade launcher may also buy grenades chosen from the grenades list. All models may buy armour from the armour list.

Veteran-type squad: 7 points each
M WS BS S T W I A Ld
4  4  4 3 3 1 4 1  8
weapons: none
You may buy each model one weapon from the basic weapons list, one weapon chosen from the assault weapons list and any number of grenades from the grenades list. Up to two models may replace their basic weapon with a special or heavy weapon. All models may buy armour from the armour list.

Juve-type squad: 3 points each
M WS BS S T W I A Ld
4  2  2 3 3 1 3 1  6
weapons: none
You may buy each model weapons chosen from the assault weapons section of the wargear list. Each model may buy flak armour at a cost of 1 point.

Scout-type squad: 6 points each
M WS BS S T W I A Ld
4  3  3 3 3 1 3 1  7
weapons: none
You may buy each model one weapon from the basic weapons list and one weapon chosen from the assault weapons list, or as many assault weapons as you wish. You may also buy any number of grenades from the grenades list. Up to two models may replace their basic weapon with a special or heavy weapon. All models may buy armour from the armour list.
This squad may infiltrate.

Specialist squad: 7 points each
M WS BS S T W I A Ld
4  3  3 3 3 1 3 1  7
weapons: none
You may buy each model one weapon from the basic or special weapons list and one weapon chosen from the assault weapons list. You may also buy as many grenades from the grenades list as you wish, and armour.

Vehicles:
Up to 50% of your army
Support weapons:
up to 25% of your army

Mortar: 30 points each
Crew
M WS BS S T W I A Ld
4  3  3 3 3 1 3 1  7
The mortar works in exactly the same way as a twentieth century mortar, and is used for blasting troops out of cover and providing long distance support. It has two crewmen.

Spider turret: 10 points each
Crew
M WS BS S T W I A Ld
4  3  3 3 3 1 3 1  7
The Spider is equipped with either twin-linked heavy stubbers (+20 points) or twin-linked heavy bolters (+40 points). The spider has two crewmen.

Devastator AAC: 70 points each
Crew
M WS BS S T W I A Ld
4  3  3 3 3 1 3 1  7
The Devastator AAC is a large mobile turret mounting a quad-linked autocannon. It is designed to shoot down aircraft and destroy vehicles, a task at which it is highly effective. It has three crewmen.

Conversion Beamer: 50 points each
Crew
M WS BS S T W I A Ld
4  3  3 3 3 1 3 1  7
The conversion beamer is a weapon that converts mass to energy, making it supremely adept at destroying heavily armed targets. They are very rare, and must be used with great precision, as they are practically useless against fast moving targets. It has two crew members. 

Visions of the Emperor
He would have to go into battle again tomorrow. A never-ending round of death and carnage. Was the future really worth all the suffering he had to bring about?
The man who would in later years become known as merely the Emperor toyed with his Bolt Pistol. He was torn apart inside. Was he really doing the right thing? He knew he was heralding in the future, mankind's destiny, but was it the right one? Many lives would be lost on the way, and he would be responsible for them, for he would have to guide man's path back into the stars. 
And it wasn't a pretty thought, the future. If he was bringing in some bright shining realm, full of good, he wouldn't have a problem. But his own psychic powers were betraying him, trying to drive him insane by showing him his future. At times, he could see it all before him, and could not help feeling revulsion at what he was creating. An opressive regime more powerful and frightning than mankind had ever produced before. Manifold horrors and tortures for those who merely happened to be born with a certain kind of mind, a desire for the freedom every man should have. It was barely better than what this evil empire was preventing. Was Chaos really as evil as he believed?
No, he couldn't think like that. He had to carry on fighting, looking for a way out of the trap of fate that had been laid for him. Had to concentrate, get a grip on himself.
He could see it all now. Steam drifted across his face as surveyed the scene of carnage. Corpses lined the walls, dressed in armour he recognised, but had never before been built. The stench of blood was everywhere, and he could sense a psychic lingering, hungering for more blood, more carnage. He moved on.
As he turned round corners into scenes yet more and more horrific, he walked into a large chamber. On the floor lay the form of an angel, broken. Once again, he recognised this. Was he to create this angel lying before him in a pool of blood? And then he looked up, into the eyes of a true monster. The creature was wearing armour similar to his own, but twisted. The Emperor's armour was shining white, but this horrific creation was garbed in red, black and brass. From his hands came two massive metal claws, surging with power. And yet, recognition flashed for a third time. Was this monster also his own creation? The creature also recognised him, and then a flash of pure evil crossed it's eyes.
With a screamed battle cry, combat was joined. It was a raging heat, crossing dimensions as the two battled each other's bodies and minds. Blows were struck, some almost crippling, but the two fought on, unable to give up. This was a battle of titans, as if the fate of the galaxy would be decided by it.
And then it was over. All around him was nothing but the void. He felt empty, crushed, defeated. Was this what it was like to die? A part inside him knew all too well. And then a sudden surge of energy rushed through him, the pure power of belief. He wasn't dead, he was all-powerful. And he hungered - for human souls.
Overcome by these visions of horror, the most powerful creature on Earth screamed, the sheer agony coursing through his veins, trying to regain control of himself. Was all this really going to happen?