Systems, methods, and devices for playing wagering games with symbol clumps and non-uniform weighting of reel positions

Gaming devices, gaming systems, methods of conducting wagering games, and computer programs for executing wagering games are disclosed. A gaming system is disclosed which includes one or more processors and one or more memory devices storing instructions that, when executed by at least one of the processors, cause the gaming system to: receive a wager to play a wagering game with symbol-bearing reels, each of which has distinct reel positions populated by various symbols, at least one reel bearing a symbol clump; and, display via a display device a randomly determined outcome of the wagering game. Each wagering-game outcome includes predetermined symbols occupying distinct array positions in a displayed array. Each reel position has a weighted probability of occupying an array position in the array. The weighted probabilities are configured such that the symbol clump, when part of a wagering-game outcome, can only land in its entirety in the array.