Gaming system and method of gaming

1. A gaming system for play of a game, the gaming system comprising:

a credit input mechanism configured to receive a physical item associated with a monetary value for establishing a credit balance, the credit balance being increasable and decreasable based at least on wagering activity;

a display having a display area;

a memory storing data indicative of

(1) a set of base symbols, each base symbol having a predefined location in said set relative to others of said base symbols,

(2) a plurality of symbol patterns of symbols, defining a plurality of numbers of symbols and a plurality of types of symbols that are to be removed from the set of base symbols, each symbol pattern corresponding to a different win outcome probability, and

(3) a weighted table configured to define a relative selection of each of said symbol patterns;

a game controller, said game controller comprising a selector configured to, in accord with the wagering activity,

randomly select one of said symbol patterns including a first number of the numbers of symbols and a first type of the types of symbols using the weighted table,

remove the first number of the first type of symbols from the set of base symbols in accordance with the selected one of said symbol patterns so as to define a modified set of symbols,

initiate a game and select for the game a plurality of base symbols from the modified set of symbols;

display on said display area the selected plurality of base symbols from the modified set of symbols; and

an outcome evaluator configured to determine a game outcome based on the selected base symbols from the modified set of symbols.

2. A gaming system as claimed in claim 1 , wherein symbols of the plurality of patterns of symbols define removable symbols in a removable symbol set and are defined according to desired conditional probability chains between symbol groups that produce desired win probability outcomes.

3. A gaming system as claimed in claim 1 , wherein symbols of the plurality of patterns of symbols define a removable symbol set and include a locations of removable symbols relative to the base symbol set.

4. A gaming system as claimed in claim 1 , wherein at least some of the plurality of patterns of symbols correspond to different win outcome probabilities.

5. A gaming system as claimed in claim 1 , wherein the weighted table is one of a plurality of weighted tables, and the game controller is further configured to select any one of the weighted tables.

6. A gaming system according to claim 1 , wherein said selector comprises a symbol selector and symbol pattern selector.

7. A method of gaming for use with a gaming machine having a credit input mechanism configured to receive a physical item associated with a monetary value for establishing a credit balance, the credit balance being increasable and decreasable based at least on wagering activity, a display having a display area, a memory storing data indicative of a) a set of base symbols, each base symbol having a predefined location in said set relative to others of said base symbols, b) a plurality of symbol patterns of symbols defining a plurality of numbers of symbols and a plurality of types of symbols that are to be removed from the set of base symbols, each symbol pattern corresponding to a different win outcome probability, and a weighted table configured to define a relative selection of each of said symbol patterns, and a game controller, the method comprising:

establishing a credit balance via said credit input mechanism receiving the physical item;

in accord with the wagering activity, randomly selecting via the game controller one of said symbol patterns including a first number of the numbers of symbols and a first type of the types of symbols using the weighted table;

removing via the game controller the first number of the first type of symbols from the set of base symbols in accordance with the selected one of said patterns of symbols so as to define a modified set of symbols;

initiating a game and selecting for the game via the game controller a plurality of base symbols from the modified set of symbols;

displaying on said display area the selected plurality of base symbols from the modified set of symbols; and

determining via the game controller a game outcome based on the selected base symbols from the modified set of symbols.

8. A method as claimed in claim 7 , wherein the symbols of the plurality of patterns of symbols define removable symbols in a removable symbol set, and the method further comprising defining symbols in the removable symbol set according to desired conditional probability chains between symbols that produce desired win probability outcomes.

9. A method as claimed in claim 7 , wherein symbols of the plurality of patterns of symbols define a removable symbol set and include a pattern of symbols defining locations of removable symbols relative to the base symbol set.

10. A method as claimed in claim 7 , wherein at least some of the plurality of patterns of symbols correspond to different win outcome probabilities.

11. A method as claimed in claim 7 , wherein the weighted table is one a plurality of weighted tables, and the method further comprising selecting any one of the weighted tables to use.

12. A method as claimed in claim 7 , wherein said selector comprises a symbol selector and symbol pattern selector.