Farm
Farming is the repetitive killing of monsters which present little or no challenge to the player for the purpose of earning experience and winning treasure (at no risk).
Farming is widely considered to be abusive play as it upsets the game balance if players can get items and experience for free.
Games with non-persistent levels or games that feature self-reproducing monsters are most susceptible to farming. Perhaps the quintessential example is worm-farming in Angband. Angband features a catagory of monsters known as "worm masses" which will divide to create more worms. A high level player surrounded by worms can level up ad infinitum by placing a marble on one of the arrow keys of his keyboard, causing the PC to continually attack the masses, and come back several hours later to find his character seriously leveled up.
Countermeasures
Some of the more common countermeasures developers implement to prevent or discourage farming:
- Grant little or no experience when the level difference between the PC and a monster is larger than some threshold
- Grant experience only for the first N monsters of one type that a player kills
- Make dungeon trips one way (all stairs go down - no way revisit ealier levels)
- Detect farming behavior directly and punish the player through divine retribution
- Disallow infinitely reproducing monsters
- Disallow stair dancing by limiting the frequency a player may use a set of stairs