Stacks of sticky wild symbols

Abstract

A slot game tracks a number of special symbols through multiple spins and unlocks game windows and/or stacks of sticky wild symbols based on the number of tracked special symbols meeting or exceeding a threshold value. Each stack of sticky wild symbols replaces a given reel for the remainder of the game or instance, such that that reel will no longer receive a random outcome and can no longer land special symbols as display symbols. As more special symbols are accumulated, more game windows will be unlocked and more stacks of sticky wild symbols will be placed on the game windows.

What is claimed is: 
     
         1 . A gaming system comprising:
 a display system; and   a game controller comprising one or more processors, the one or more processors executing instructions which cause the game controller to:
 control the display system to display a first unlocked game window including a reel grid; 
 randomly determine, using a random number generator, display symbols for the reel grid, the display symbols selected from a first symbol set including a plurality of special symbols; 
 track, by a special symbol meter, accumulated special symbols, wherein accumulated special symbols are special symbols that land as display symbols on the reel grid over a period of spins; 
 in accordance with a number of accumulated special symbols tracked by the special symbol meter satisfying a first threshold of accumulated symbols:
 replace one or more reels of the reel grid with a stack of sticky wild symbols that remain in a same reel position for all remaining spins of a current game instance, such that each stack of sticky wild symbols prevents the one or more reels from landing special symbols for subsequent spins; and 
 control the display system to display the stack of sticky wild symbols. 
 
   
     
     
         2 . The gaming system of  claim 1 , wherein the instructions further cause the game controller to, responsive to the number of accumulated special symbols tracked by the special symbol meter satisfying a first threshold of accumulated symbols:
 unlock a second game window including a reel grid;   control the display system to display the first unlocked game window and the second unlocked game window; and   randomly determining, using a random number generator, display symbols for the reels of the first unlocked game window and the second unlocked game window for each of the subsequent spins.   
     
     
         3 . The gaming system of  claim 2 , wherein:
 display symbols for the second unlocked game window are randomly selected from a second symbol set including a plurality of the special symbols; and   replacing a reel of the reel grid with a stack of sticky wild symbols includes:   replacing one or more reels of the reel grid of the first unlocked game window with the stack of sticky wild symbols; and   replacing one or more reels of the reel grid of the second unlocked game window with the stack of sticky wild symbols.   
     
     
         4 . The gaming system of  claim 3 , wherein:
 the one or more reels of the first unlocked game window is a second reel of the reel grid of the first unlocked game window, such that the second reel of the first unlocked game window is a stack of sticky wild symbols for the subsequent spins; and   the one or more reels of the second unlocked game window is a second reel of the reel grid of the second unlocked game window, such that the second reel of the second unlocked game window is a stack of sticky wild symbols for all subsequent spins.   
     
     
         5 . The gaming system of  claim 4 , wherein the instructions further cause the game controller to:
 unlock a third level responsive to an updated number of special symbols tracked by the special symbol meter satisfying a second threshold of accumulated special symbols;   unlock a third game window including a reel grid responsive to unlocking the third level;   replace the second reel of the third unlocked game window with a stack of sticky wild symbols that remains in the same reel position for all remaining spins; and   for each subsequent spin, randomly determine, using a random number generator, display symbols for the third unlocked game window, the display symbols selected from a third symbol set including a plurality of the special symbols.   
     
     
         6 . The gaming system of  claim 5 , wherein the instructions further cause the game controller to:
 unlock one or more subsequent levels responsive to achieving one or more subsequent thresholds of accumulated special symbols, wherein the accumulated special symbols are special symbols that land as display symbols of a group consisting of the first unlocked game window, second unlocked game window, and third unlocked game window over a period of spins;   replace one or more additional reels of one or more of the unlocked game windows with a stack of sticky wild symbols, wherein each stack of sticky wild symbols remains in its reel position for all subsequent spins; and   for each subsequent spin, randomly determine, using a random number generator, display symbols for the reels of the group consisting of the first unlocked game window, second unlocked game window, and third unlocked game window except for each reel having a stack of sticky wild symbols.   
     
     
         7 . The gaming system of  claim 6 , wherein the first symbol set has a higher return to player (“RTP”) than the second or third symbol sets. 
     
     
         8 . The gaming system of  claim 6 , wherein:
 the first symbol set comprises a first plurality of reel strips corresponding to the reels of the first unlocked game window;   the second symbol set includes a second plurality of reel strips corresponding to the reels of the second unlocked game window;   the third symbol set includes a third plurality of reel strips corresponding to the reels of the third unlocked game window; and   one or more reel strips of the first plurality of reel strips include more wild symbols than one or more reel strips of the third plurality of reel strips.   
     
     
         9 . The gaming system of  claim 8 , wherein the instructions further cause the game controller to:
 replace a reel corresponding to a first reel strip with the stack of sticky wild symbols before replacing a second reel strip with a stack of sticky wild symbols in accordance with the first reel strip having more wild symbols than the second reel strip.   
     
     
         10 . The gaming system of  claim 1 , wherein the instructions further cause the game controller to control the display system to display a representation of the special symbol meter with an indication of the accumulated special symbols over the period of spins. 
     
     
         11 . A gaming system, comprising:
 a user interface system configured for receiving an indication to initiate one or more instances of a slot game;   a display system comprising one or more displays; and   a control system comprising one or more processors, wherein the one or more processors execute instructions which cause the control system to perform operations comprising:
 receive, via the user interface system, an indication to initiate a spin of the instance; 
 randomly selecting, using a random number generator, display symbols for reels of a first game window, wherein the display symbols are randomly selected from a first set of reel strips, each reel strip of the first set of reel strips corresponding to a reel of the first game window; 
 tracking, by a special symbol meter, special symbols that land as display symbols over multiple spins of the instance to determine a number of tracked special symbols; 
 responsive to the number of tracked special symbols meeting or exceeding one or more threshold values: 
 replacing one or more reels of the first game window with a stack of sticky wild symbols; 
 unlocking a second game window; and 
 controlling the display system to display the stack of sticky wild symbols in place of the one or more reels for any remaining spins of the instance. 
   
     
     
         12 . The gaming system of  claim 11 , wherein executing the instructions causes the control system to perform operations further comprising:
 using a first reel strip of the first set of reel strips for a first reel of the first game window; and   using a second reel strip of the first set of reel strips for a second reel of the first game window; and   wherein the reel corresponding to the first reel strip is replaced with the stack of sticky wild symbols before the second reel strip in accordance with the first reel strip having more wild symbols than the second reel strip.   
     
     
         13 . The gaming system of  claim 12 , wherein executing the instructions causes the control system to perform operations further comprising:
 using a third reel strip of the first set of reel strips for a third reel of the first game window;   wherein the second reel strip has more wild symbols than the third reel strip; and   wherein the reel corresponding to the second reel strip is second to be replaced with the stack of sticky wild symbols.   
     
     
         14 . The gaming system of  claim 11 , wherein executing the instructions causes the control system to perform operations further comprising:
 randomly selecting, using a random number generator, display symbols for reels of the second game window, wherein the display symbols are randomly selected from a second set of reel strips, each reel strip of the second set of reel strips corresponding to a reel of the second game window.   
     
     
         15 . The gaming system of  claim 14 , wherein:
 unlocking the second game window includes one or more reels of the second game window replaced with a stack of sticky wild symbols that replaces the one or more reels for remaining spins of the instance; and   randomly selecting display symbols for reels of the second game window, includes randomly selecting display symbols for all reels of the second game window except for the one or more reels replaced with a stack of sticky wild symbols.   
     
     
         16 . The gaming system of  claim 15 , wherein:
 the second game window includes a stack of sticky wild symbols in a reel position that corresponds to a reel position of a stack of sticky wild symbols in the first game window.   
     
     
         17 . The gaming system of  claim 11 , wherein once the second game window is unlocked, the first game window and the second game window are both in play for remaining spins of the instance. 
     
     
         18 . The gaming system of  claim 11 , wherein executing the instructions causes the control system to perform operations further comprising:
 randomly determining, using a random number generator, a total number of possible levels, wherein each level corresponds to a threshold value of the one or more threshold values for tracked symbols.   
     
     
         19 . One or more machine-readable devices storing instructions, wherein the instructions when executed by one or more processors, cause performance of operations, comprising:
 randomly selecting, using a random number generator, display symbols for each reel of a reel grid of a first unlocked game window, the display symbols for each reel of the reel grid selected from a corresponding reel strip, each reel strip including a plurality of special symbols and having a value;   tracking, by a special symbol meter, accumulated special symbols, wherein accumulated special symbols are special symbols that land as display symbols on the reel grid over a period of spins;   advancing to a first level responsive to meeting or exceeding a first threshold of accumulated special symbols tracked by the special symbol meter; and   responsive to advancing to the first level, assigning the reel of the reel grid with a stack of sticky wild symbols that persists in place of the reel for all remaining spins of a game instance.   
     
     
         20 . The one or more machine-readable devices storing instructions of  claim 19 , wherein the instructions when executed by one or more processors, cause performance of operations, further comprising:
 advancing to a second level responsive to meeting or exceeding a second threshold of accumulated special symbols; and   responsive to advancing to the second level, unlocking a second game window including a reel grid comprising a stack of sticky wild symbols in place of one reel.