Display of symbol accumulation in reel-type games

Machines (50), servers (62) and reel-type games are disclosed which provide a player with a visible indication (16) of progress being made towards award of a stacked or expanding symbol (24) on a reel (12), thereby heightening anticipation and increasing excitement of the game. This is achieved by providing a trigger mechanism or condition for appearance of the stacked or expanding symbol in which the required trigger condition can be achieved (i.e. accumulated or collected) over multiple turns or spins of the game, and by providing a display of the progress towards meeting the trigger condition to the player directly on the display (52) of the game. The symbol set for the game includes a progress symbol (22) associated with progress towards an award of the expanded or stacked symbol (24). The progress symbol (22) causes an activation of an accumulation indicator (16) provided on the display (52). The accumulation indicator (16), or set of such indicators (20A, 20B, 20C, 20D), provides a display of the progress towards meeting the trigger condition.