Gargoyle's Quest: Ghosts'n Goblins (Japanese: レッドアリーマー 魔界村外伝, Hepburn: Reddo Arīmā Makaimura Gaiden, "Red Arremer: Demon World Village Side-Story"), is a platform/side scrolling adventure game with mild role-playing video game elements from Capcom. It was released on May 2, 1990 in Japan and then in the United States and Canada in July. The main character Red Arremer (Firebrand in the US) made his debut in the video game series Ghosts'n Goblins. Gargoyle's Quest was followed by two sequels, a NES game Gargoyle's Quest II in 1992 and Demon's Crest for the SNES in 1994.

The game consists of two types of areas: an overhead view where Firebrand traverses the Ghoul Realm, either on the world map or in towns, and individual, side-scrolling, battle levels which feature a boss at the end. In between actual levels, as Firebrand traverses the overhead map of the Ghoul Realm, he is susceptible to random encounters like a typical console RPG. He must defeat the enemies in order to return to the overhead-view map. There are also ghouls that can be encountered that spark a small battle level which the player must defeat in order to get past them.

Firebrand can walk, jump (varying heights depending on items obtained), cling to walls, fly (a hovering ability actually) for a period of time determined by the items the player has obtained, and fire projectiles (the only method of offense in the game). The player starts with one type of projectile: it does not travel very far, and has limited power. Eventually, the player will gain new projectiles, discussed below. Firebrand has a small number of hit points, starting at two and increasing throughout the game based on items or blessings obtained; various enemies and objects drain different amounts of hit points.

As the user progresses, various items are gained which have differing effects. Some items are passive; they increase Firebrand's abilities outright. For example, the Fingernail of the Spectre increases his jumping ability for the remainder of the game, and there are several items that increase the length of time which Firebrand can fly, the final of which allows for him to fly infinitely. There are also items which can be used as needed, such as items to restore health. Additionally, several types of projectiles are obtained throughout the game. All can be offensive tools to defeat enemies, but each has different traits or specialized uses. The Blockbuster, for example, which is the first projectile obtained after the Firebrand's starting projectile, is twice as powerful, travels further, and can break special blocks the player may need to pass. Another projectile temporarily creates objects which Firebrand can jump from to reach necessary locations. This block-breaking power and other useful abilities leaves a use for such projectiles throughout the game, even when more powerful projectiles are obtained. Projectiles can be selected one-at-a-time from the select menu, as can items such as healing vials.

In the final boss battle, the player makes a choice which results in one of two scenarios for how the final battle is played. In one scenario, the player is stripped of all ability boosting items and powers, leaving him virtually unable to win, and must then fight the final boss. In the other scenario, resulting from the other choice, the player maintains these items and powers, and attempts to defeat the final boss and win the game.