1. A method of gaming comprising: (a) selecting a plurality of symbols from a source symbol set to form a selected symbol set for display at a plurality of display positions, the source symbol set comprising at least one removable symbol and at least one designated symbol different to each removable symbol; and if a removal condition is met, the removal condition including at least that the selected symbol set includes at least one designated symbol within the display positions; (b) removing at least one removable symbol from 15 the source symbol set from which it was selected to form a modified source symbol set; (c) selecting at least one symbol from the modified source symbol set to form a modified selected symbol set; and (d) determining whether to make an award based on the modified selected symbol set.