IronArcturus: Hostile Waters: Antaeus Rising - This is a 3rd-person perspective game where you can pilot multiple tanks and aircraft. It was very ahead of its time and should have had a sequel.
I'll second Hostile Waters, although that description doesn't really do it justice. There are more types of vehicles, and you can customize them all (different weapons, armor). While you
can pilot them, and often will, you can also assign various AIs to control them, each with a different personality and specialty. You then command the AIs. You will also need to handle resource gathering in order to produce more vehicles. At heart, the game is an RTS.
Sacrifice is cut somewhat from the same cloth. Also basically a 3rd person RTS. You control a wizard who, having travelled to a new world (because his magical experiments ultimately resulted in the destruction of his own), gets involved in a conflict between 5 gods.
The game consists of ten missions, and you choose which god to do a mission for in each case. As such, there are 50 missions in all, but you will only play 10 of them in any given playthrough. Which missions you choose along the way affects the story as well as your arsenal. Depending on your choices, some gods may become unavailable for further missions along the way.
In a mission, you will be fighting wizards working for other gods. Each wizard (you included) has an altar to his or her god. The ultimate object of each mission is to make a sacrifice (hence the name of the game) to your own god on each enemy wizard's altar, thus banishing them from the realm. Combat consists of a combination of magic spells and summoned creatures. Each god has ten levels of spells and ten levels of creatures. For each mission you do, you get the spells and creatures of that god for that level, and those will be available to you for the rest of the game. As such, depending on which gods you choose to work for in which order along the way, your arsenal of spells and creatures may look radically different from game to game.
All these things also mean that the game has excellent replayability. Oh, and the voice acting... It is awesome. Tim Curry as the god Stratos is fantastic.