An article of manufacture including a non-transitory computer-readable medium, having stored thereon program instructions that, upon execution by a gaming machine, cause the gaming machine to perform operations comprising:
- determining that a trigger event for a bonus game occurred during a base outcome event of a base game, wherein the base game and the bonus game are both reel-based games being executed on behalf of a client machine with a graphical display unit, wherein both the base game and the bonus game involve graphically displaying, on vertical symbol display segments of the graphical display unit, animations that simulate spinning of a plurality of reels, each reel containing a respective plurality of symbols, subsets of which are displayable in a respective vertical symbol display segment corresponding to the reel, and wherein results of the simulated spinning of the plurality of reels determine outcome events;
- in response to determining that the trigger event occurred, determining a number of pre-determined replaceable symbols for the bonus game, wherein each of the replaceable symbols, when displayed, indicates a playing card rank, and wherein the replaceable symbols are distinct from non-replaceable symbols used in the bonus game;
- adding the number of the replaceable symbols to the plurality of reels;
- and
- until all of the replaceable symbols have been replaced by non-replaceable symbols, repeatedly carrying out iterations of bonus game operations comprising:
- (i) determining a symbol set for display on the vertical symbol display segments, wherein the determined symbol set includes one or more of the non-replaceable symbols and zero or more of the replaceable symbols, and wherein the determined symbol set represents an outcome of a bonus game spin of the plurality of reels,
- (ii) causing the graphical display unit to display an animation that simulates a spinning of the reels, wherein the spinning of the reels results in the vertical symbol display segments displaying the determined symbol set,
- (iii) causing the graphical display unit to display successive replacement of each displayed replaceable symbol in the determined symbol set with either a new non-replaceable symbol or a new replaceable symbol until no displayed replaceable symbols remain on the vertical symbol display segments, wherein a particular displayed replaceable symbol is displayed on a particular vertical symbol display segment below one or more particular non-replaceable symbols, and wherein successive replacement of each displayed replaceable symbol in the particular vertical symbol display segment comprises:
- (a) selecting a new symbol to replace the particular displayed replaceable symbol,
- (b) determining a bonus payout amount associated with the particular displayed replaceable symbol,
- (c) causing the graphical display unit to display an indication of the bonus payout amount by visually transforming the particular displayed replaceable symbol into a representation of the bonus payout amount,
- (d) deleting the particular displayed replaceable symbol from the particular vertical symbol display segment,
- (e) sliding the one or more particular non-replaceable symbols down one symbol position on the particular vertical symbol display segment, and
- (f) Placing the new symbol at the top of the particular vertical symbol display segment.