I thought I'd ask a question and look forward to some insight from this very compelling community.
In a Bejeweled-like (Match 3) game, the standard behavior once a valid swap of two adjacent tiles is made is that the resulting matching tiles are destroyed, any tiles now sitting over empty spaces fall to the position above the next present-tile, and any void created above is filled with new tiles. In richer Match-3 games like Bejeweled, 4 in a row (as opposed to just 3) modifies this behavior such that the tile that was swapped is retained, turned into a "flaming" gem, it falls, and then the empty space above is filled. The next time that "flaming gem" is played it explodes and destroys the 8 perimeter tiles, triggers a different animation sequence (neighbors of those 8 tiles being destroyed look like they've been hit by a shockwave then they fall to their respective positions). Scoring is different, the triggered sounds are different, etc. There are even more elaborate behaviors for Match5, Match-cross-pattern, and many powerups that can be purchased, each which produces a more elaborate sequence of events, sounds, animations, scoring, etc...
What is the best approach to developing all these different behaviors that respond to players' "move" and her current "performance" and that deviate from the standard sequence of events, scoring, animation, sounds etc, in such a way that we can always flexibly introduce a new "powerup" ? What we are doing now is hard-coding the events of each one, but the task is long and arduous and seems like the wrong approach especially since the game-designers and testers often offer (later) valuable insight on what works better in-game, which means that the code itself may have to be re-written even for minor changes in behavior (say, destroy only 7 neighboring tiles, instead of all 8 in an explosion).
ANY pointers for good practices here would be highly appreciated.