The Legend of Zelda games feature a mixture of puzzles, action, adventure/battle gameplay, and exploration. These elements have remained constant throughout the series, but with refinements and additions featured in each new game. Later games in the series also include stealth gameplay, where the player must avoid enemies while proceeding through a level, as well as racing elements. Although the games can be beaten with a minimal amount of exploration and side quests, the player is frequently rewarded with helpful items or increased abilities for solving puzzles or exploring hidden areas. Some items are consistent and appear many times throughout the series (such as bombs and bomb flowers, which can be used both as weapons and to open blocked or hidden doorways; boomerangs, which can kill or paralyze enemies; keys for locked doors; magic swords, shields, and bows and arrows), while others are unique to a single game. Though the games contain many role-playing elements (Zelda II: The Adventure of Link is the only one to include an experience system), they emphasize straightforward hack and slash-style combat over the strategic, turn-based or active time combat of games like Final Fantasy. The game's role-playing elements, however, have led to much debate over whether or not the Zelda games should be classified as action role-playing games, a genre on which the series has had a strong influence.