Catacombs is a dungeon crawler where the player has to find his way through randomly generated dungeons while collecting as much gold as he can. Little of the dungeon is shown when starting so the player has to explore to find the exit and move on to the next level in the dungeon. Sometimes it’s necessary to dig tunnels through walls to get forward.
The player only has one statistic, strength, and it constantly decreases. When it reaches zero the player dies and has to start over in a new dungeon. To increase the strength the player has to collect food. The dungeons are full of monsters that the player can combat. Battles are automatic and the only option available for the player is to run away. The outcome of battles depend on strength as it decreases for each hit. Winning a battle leads to an increase in strength. There are also traps to watch out for. When stepping on one, the player has five chances to guess a number and if he succeeds he will saved. The player can also come across phantoms which can be paid to increase strength.