This is a standard annihilation battle, with us deploying along the short edges of our 3'x5' table (be nice to get a proper 4'x6' soon) Nids got the first turn.
Forces:
Necromundan 124th, 2nd company
C 1 - Chimera (heavy flamer and multi-laser) with Veteran Squad (10), armed with 3 plasma guns, a heavy weapons team (autocannon) and lasguns.
C 2 - Chimera (heavy flamer and multi-laser) with Ogryn squad (5) with Bone 'Ead and Ripper Guns.
C 3 - Chimera (heavy flamer and multi-laser) with Veteran Squad and Primaris Psyker (10) armed with 3 plasma guns, a heavy weapons team (autocannon) and lasguns.
M1/M2 - Medusa Siege Tank, extra armour, enclosed crew compartment
Hive Fleet Colossus, Vitor sector splinter
H.T - Hive Tyrant with things I can't remember.
C1 - Carnifex with twin-linked devourers with brainleech worms, scything talons, mysetic spore 1
T-Trygon
W 2 - Tyranid Warriors (4) with Venom Cannon and Devourers, mysetic spore 2
R-Ripper Swarm (5)

Nids Turn 1
Both the Hive Guard and the Tyrant moved and ran towards the central building, while the Rippers advanced into the rear building and went to ground (where they stayed the whole game)
IG turn 1
Chimeras 1,2 and 3 all moved up 6" and inflicted a wound on the Hive Guard.
Medusa 2 moved 12" behind the forward building to get a better shot next turn.
Medusa 1 fired on the Hive guard and inflicted 2 wounds, but they made their cover saves.
Nid turn 2
The Tyrant ran forward next to the central building and the Hive Guard emerged from the other side of the building and fired on chimera 1, immobilizing and stunning it.
In a rain of mysetic spores, Carnifex 1 appeared behind chimera 2 and wreaked it, and the Warriors emerged from their own spore next to Medusa 1 and fire on its side armour to no effect.
The Trygon rose up from the ground next to the central building in front of the Tyrant.
IG turn 2
The Ogryns bailed from the wreck of Chimera 2 and were pinned.
Medusa 2 moved back 12"
Chimera 3 fired on the Trygon, 2 plasma gunners died as their weapons cooked off, and the auto cannon inflicted 2 wounds
To round off the turn Medusa 1 fired point blank into the Warriors and made a direct hit and killed 3, leaving 1 warrior left.
Nids turn 3
The first Mysetic Spore fired on the Ogryns and inflicted 2 wounds, while the 2nd Spore fired on Chimera 1 blowing it up and killing 6 of the Guardsmen inside.
The Hive Guard fired on Medusa 1 which blew up.
The carnifex fired on the Ogryns, causing another 2 wounds and killing 1 before charging them, killing one more(2wounds) and receiving a wound in return and the Ogryns fled.
The Trygon assaulted Chimera 3 which was wrecked
The remaining Warrior charged the 4 guardsmen from the wreck of chimera 1 and in a spectacular display of epic fail inflicted 0 wounds! and received one in return
IG turn 3
the Ogryns fell back towards the left board edge (their path to my edge was impeded
Medusa 2 fired on the Carnifex, wounding it and the nearby Mysetic Spore.
The squad with the Primaris ran from their wrecked chimera into the nearby building.
The combat between the Warrior and the other vet Squad continued, taking 3 wounds from the Warrior and the Sergeant putting one on the Warrior, before fleeing and being wiped out.
Nids turn 4
the Carnifex and Warrior advance on the remaining Medusa and fire on it, the Warrior shook it and the Carnifex blew it up, but was too close and received a wound.
The Hive Guard advanced and fired on the Ogryns, killing another.
the Tyrant fired on the Prymaris squad killing 1, and used its Peroxym psychic power on the squad, nerfing them down to WS1.
The Trygon then charged the squad and killed them all.
IG turn 5
The fleeing Ogryns; my last unit on the field, fled 5" and fired on the mysetic spore inflicting 2 wounds.
Nid turn 5
the Nids all moved towards the Ogryns and fired on them but did nothing.

Now in control of the Eastern Grasslands the Nids are in a position to hit the main line across the river. However, in their mad rush for the rich biomass of the northern mining collective to the west their flanks are exposed. Will Colossus smash through the heavily defended imperial lines or will the imperium hold them off and strike the beasts soft underbelly? Only time will tell...
Nids-8, IG-0. Well that was yet another craptacular performance by yours truly. Feel free to comment, particularly on how to make a list that can kill all his stuff in the turn before my things die. Im guessing 80 guardsmen(6 las cannons) and an executioner ought to do it, but help is very, very appreciated.