Gaming system, gaming device method providing symbol upgrades

In various embodiments, the gaming system, gaming device, and gaming method disclosed herein provides a slot or reel game which includes one or more reel upgrade triggers. When the reel upgrade trigger occurs in or for a play of a game, one or more of the reels are changed for that play of the game. For each changed reel, the reel upgrade trigger cause that reel to be changed such that the player is more likely to obtain one of the winning symbol combinations in the play of the game, and/or such that a higher award is associated with one of the symbols on that reel in the play of the game. In one embodiment, the reel upgrade trigger causes each of the reels which have not displayed any symbol yet for the play of the game (i.e., reels that are still spinning) to change to a better reel strip for the play of the game. In another embodiment, the reel upgrade trigger causes one or more of the reels which have displayed a symbol for the play of the game to change to a better reel strip for the play of the game.