 Aside from the two protagonists, the game introduces Captain Qwark, who appears in the following games, as both an enemy and ally.The game introduced features such as the ability to purchase items, weapons and unlocking gadgets as the game progresses, which have become a staple of the series in following games.The first in this series does not feature the upgrade system of experience earned for enemies killed; instead, the player may purchase stronger, gold versions of select weapons using a combination of hidden Gold Bolt items and regular bolts after finding a secret area in the game.