Half-Life 2 + Episodes 1 and 2 + Portal + Team Fortress 2
Innovative Portal aside, this sets new standard for value. Each of the five elements could be a full game in its own right.
Though rumors originally suggested that you'd be a photographer snapping the wildlife in Afrika, it's now being hinted that Sony's safari piece might be an integral part of Home, allowing you to jump from your house to the grassland for a wander round. No word on whether you can be eaten, mind you, but we'll bring you news once we get it.
Be sure to check outpart two of our feature.