Rival Realms (1998)

The game has three races to choose from: Humans, Elves, and Greenskins. Each race has its own characteristics and units just as is found in most RTS games. However, that's just the beginning. Your armies are always unique. Every single unit can gain up to five levels of experience and has its own inventory that can be traded between units. Inventory items include skill artifacts, keys, potions, spell scrolls, and more.