Here is the full list of all 10 Ogre achievements.
Have 10+ units (armour or infantry) fire on the same turn.
Win all of the original Ogre scenarios at least once.
Win all of the G.E.V map scenarios at least once.
Complete the Nightfall campaign.
Win 5 scenarios as the North American Combine.
Win 5 scenarios as the Pan-European Federation.
Destroy an enemy Ogre in Overrun.
Destroy 3 units with spillover fire.
Deploy reinforcements when down to one remaining unit.
Destroy or disable an Ogre using only Infantry or MBS units.