Warhammer 40,000: Dawn of War: Winter Assault/Blood for the Blood God!

Orks
The Orks part is very straightforward. You have some troops – some (mostly melee) infantry, Killa Kans and Wartraks – no build capacity, and although you have some resources, your Squad Cap is already over the top so you cannot reinforce unless you get most of your infantry killed. Your goal is to kill Sturnn, who is found near the Field Command marked with red, meaning just a short way from where you start.

You will be met with a squad of Ogryns, lots of Guardsmen Squads, Heavy Bolter Turrets and some vehicles (mostly Hellhounds and a Leman Russ Tank). Just try to use your units reasonably; don't send Slugga Boy Squads to beat on Hellhounds. Keep your Wartraks back to hit the Sentinels and Turrets and try to save them for the Leman Russ, who should be beat with a couple of Killa Kans at the same time. Killa Kans are also good for the Turrets and, well, everything. Your heavy melee infantry and a passing Killa Kan should make short work of the Guardsmen Squads.

When you get close to the Field Command and find Sturnn, just focus on him to get it over with. Your Warboss and the closest Killa Kan should take him out effortlessly on Normal even if you're shot at while doing it. When Sturnn is down, the part is over and you switch to Chaos Space Marines.