Systems and methods for providing a feature game

1. A gaming machine comprising:

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

credit meters configured to monitor the credit balance;

a memory configured to store a set of symbols including a plurality of standard symbols and a trigger symbol;

a symbol selector configured to, in accord with the wagering activity, select a plurality of symbols from the set of symbols for display during play of a base game;

a display configured to display the selected symbols;

an outcome evaluator configured to monitor play of the base game, wherein a feature game is triggered in response to a trigger event including a trigger symbol being displayed during the base game, the feature game having a predefined rule, wherein the predefined rule is defined by a first component comprising a number of free games and a second component comprising an average prize amount; and

a rule modifier configured to modify the predefined rule in response to a determination that the predefined rule is to be modified before play of said feature game, including to adjust at least one of the first component and the second component;

a controller configured to initiate play of said feature game based on the modified rule; and

wherein the average prize amount for the predefined rule is defined at least in part by a plurality of prize multipliers, and wherein adjusting the average prize amount comprises selectively deactivating at least one of said plurality of prize multipliers; and

a payout mechanism configured to provide any award in response to determining that an award is to be made.

2. A gaming machine according to claim 1 , and wherein said trigger event comprises a random determination independent of said at least one trigger symbol.

3. A gaming machine according to claim 2 wherein when a random determination independent of the trigger symbol is triggered, a plurality of selectively revealable objects are displayed, at least one of which, when selectively revealed, triggers both said feature game and said modifying of the predefined rule.

4. A gaming machine according to claim 1 , and wherein said feature game comprises a plurality of selectable play options, each of the plurality of play options being associated with respective ones of a plurality of predefined rules.

5. A gaming machine according to claim 1 , and wherein modifying the first component comprises adjusting the number of free games.

6. A gaming machine comprising:

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

credit meters configured to monitor the credit balance;

a memory configured to store a set of symbols including a plurality of standard symbols and a trigger symbol;

a symbol selector configured to, in accord with the wagering activity, select a plurality of symbols from the set of symbols for display during play of a base game;

a display configured to display the selected symbols;

an outcome evaluator configured to monitor play of the base game, wherein a feature game is triggered in response to a trigger event including a trigger symbol being displayed during the base game, the feature game having a predefined rule; and

a rule modifier configured to modify the predefined rule in response to a determination that said at least one predefined rule is to be modified before play of said feature game, wherein said determination is implemented a) randomly after the plurality of symbols have been selected for display, and b) by controlling the display to selectively superimpose at least one overlay symbol over the displayed symbols, wherein said predefined rule is modified in response to said overlay symbol being superimposed over said trigger symbol; and

a controller configured to initiate play of said feature game based on the modified rule.

7. A gaming machine according to claim 6 wherein said overlay symbol is only superimposed over a predefined location.

8. A method of gaming for use with a gaming machine having a credit input mechanism configured to receive a physical item representing a monetary value for establishing a credit balance, the credit balance being increasable and decreasable based at least on wagering activity, credit meters configured to monitor the credit balance, a memory configured to store a plurality of symbols, a display, a payout mechanism, and a game controller having a symbol selector, an outcome evaluator, and a rule modifier, the method comprising:

selecting, using the symbol selector, in accord with the wagering activity, a plurality of symbols from the set of symbols for display during play of a base game;

controlling, using the controller, the display to display the selected symbols;

monitoring, using the outcome evaluator, play of the base game, wherein a feature game is triggered in response to a trigger event including a trigger symbol being displayed during the base game, the feature game having a predefined rule; and

modifying, using the rule modifier, the predefined rule in response to a determination that said at least one predefined rule is to be modified before play of said feature game, wherein said determination is implemented a) randomly after the plurality of symbols have been selected for display, and b) by controlling the display to selectively superimpose at least one overlay symbol over the displayed symbols, wherein said predefined rule is modified in response to said overlay symbol being superimposed over said at least one trigger symbol; and

initiating, using the controller, play of said feature game based on the modified rule.

9. A method of gaming according to claim 8 wherein said trigger event comprises a random determination independent of said at least one trigger symbol.

10. A method of gaming according to claim 9 wherein when a random determination independent of the trigger symbol is triggered, a plurality of selectively revealable objects are displayed, at least one of which, when selectively revealed, triggers both said feature game and said modifying of the predefined rule.

11. A method of gaming according to claim 8 wherein said feature game comprises a plurality of selectable play options, each of the plurality of play options being associated with respective ones of a plurality of predefined rules.

12. A method of gaming according to claim 11 wherein each at least one predefined rule of a feature game are each defined by a first component comprising a number of free games and a second component comprising an average prize amount.

13. A method of gaming according to claim 12 wherein modifying a predefined rule comprises modifying at least one of the first component and the second component.

14. A method of gaming according to claim 13 wherein modifying the first component comprises adjusting the number of free games.

15. A method of gaming according to claim 13 wherein modifying the second component comprises adjusting the average prize amount.

16. A method of gaming according to claim 15 wherein the average prize amount for each predefined rule is defined at least in part by a plurality of prize multipliers, and wherein adjusting the average prize amount comprises selectively deactivating at least one of said plurality of prize multipliers.

17. A method of gaming according to claim 8 wherein said overlay symbol is only superimposed over a predefined location.