Halo Wars E3 2008 Demo
From Halopedia, the Halo wiki
Unlike the pre-recorded demo from E3 2007, a work-in-progress build of Halo Wars was presented by Dave Pottinger, the Lead Designer at Ensemble Studios.
Ensemble Studios showcased a game of Skirmish on the map Labyrinth, during which the player has access to the Firebase and its buildings, including the Airpad, Barracks, Field Armory, Reactor, Supply Pad, base turret, and the Vehicle Depot. Pottinger explained the basic real-time strategy gameplay and user interface, both of which have been streamlined for console. Notable additions to the RTS genre include Leader powers, which allow players to call in carpet bombing or Heal and Repair their units, and special abilities unique to each unit, such as Spartan-IIs hijacking enemy vehicles.
Certain features that appeared in the demo were cut from the final build. In one demo, the controller scheme could be seen on the top left of the sceren. Ambient life like the thorn beast appears on the map, but it was cut from the final release, along with other ambient units.