Selectable as a playable game on the Pip-Boy 3000 Mark IV, in the Inventory tab. The player starts in a tavern where they create their party, then sets off into the world in a conquest to defeat Grelok, one of many villains in the Grognak the Barbarian comics. The player's progress is saved on the holotape. The game can be played on both the Pip-Boy and terminals.
The player starts in the tavern as Grognak the Barbarian, seeking to form a band of adventurers to challenge Grelok and rid the world of his evil. The player may choose up to two companions of the available four, or for a true challenge one may attempt to go it alone. Along the path of adventure, one explores dungeons, fights monsters, and collects equipment that enhances their stats.
The game utilizes a turn-based system, each move the player makes, whether it be traveling the world map or making action in combat progresses the game; without input, the game goes nowhere fast. Each character has four attributes in this system: Hit points, Attack, Initiative, and Focus.
- Hit Points - Hit Points, or HP, is the amount of health the character has. Hit Points may be increased with defensive items such as armor or shields found across the land. Living party members restore all hit points after combat has ended.
- Attack - Attack is the base amount of damage the character does. Attack can be increased with offensive items such as weapons found across the land.
- Initiative - Initiative helps to determine a character's place in the turn order. Initiative can be increased by finding special equipment items like boots and charms. Higher initiative makes it more likely to move early, but there is no guarantee of moving first.
- Focus - Focus is used to execute special attacks, such as Grognak's Furious Rage. Focus regenerates at a rate of one point per turn in combat, but does not regenerate when on the map.
As one adventures across the map, they will see many different types of terrain. Plains, grasslands, forests, mountains, swamps, and tundras. Dotting the landscape are special structures that may be filled with monsters guarding treasure, or provide vital services like shops and Chapels of Resurrection. Shops will always provide one item to improve Hit Points, Attack, and Initiative; as well as providing a chance to restore Focus. The Chapel of Resurrection allows one to recall the souls of their fallen party members to their corporeal forms... for a price, of course.
In combat, one will face off against groups of monsters one at a time. Each monster will have a different amount of Hit Points, different Attack and Initiative, and its own unique Special Attack. Initiative is rolled every round of combat, with the highest roll going first. There is a variety of actions available to the player on their turn.
- Attack - The player character makes an Attack, dealing an amount of damage based on their Attack attribute.
- Special Attack - Each character (and monster!) has a Special Attack that they can execute for a different amount of Focus. Grognak, for example, has his Furious Rage which allows him to rapidly attack the enemy three times in a single turn. Be wary, for many monsters' Special Attacks can attack the entire party all at once!
- Meditate - Selecting Meditate puts the character into a trance for one turn that both recovers two points of Focus and reduces the damage of the next attack by one quarter.
- Restore - Choosing Restore has the character take a moment to bandage their wounds. A character who has chosen to Restore backs away from combat and is less likely to be attacked by the enemy.
- Flee - Choosing to Flee for any party member has them attempt to lead the entire party away from combat. The higher the character's Initiative, the more likely they are to successfully flee.
There are three bosses, which have the most HP compared to other enemies, while their average damage dealt is 35.
- Great Serpent - Has 400 HP and is found near the tavern in the Goblin Village in the forest.
- Stormlord - Has 420 HP and is found in a snowy area on the top of the second island.
- Grelok - The final boss, he has 280 HP and is found in the top-right area of the second island. Note that once Grelok is defeated, the game will end.
- To reach him, one needs to give a locket to an NPC in the Conjurer's Tower on the left side of the first island. This will unlock access to Foulwind Pass and subsequently to Grelok.
- Grelok is also mentioned in the text-based Reign of Grelok.
- Grognak & the Ruby Ruins can be played via the Arcade Workshop Pack cabinets.