In
wargaming and
RPG slang, "cheese" refers to some aspect of game rules that give a player an unfair advantage, usually because the designers never thought it would be used in a certain way.
For example, anyone who's ever played
Adeptus Titanicus (aka Space Marine, Epic 40,000, Epic 40K) will agree that the
Ork Gargant's
ball weapon is far too destructive for its points value and unfairly skews the game to the Ork player's advantage - it's "cheesy". So are some of the slightly over-the-top artifacts you pick up in a home-made
Dungeons & Dragons campaign, and the extra-cheap-but-extra-powerful
Clan weapons in
BattleTech.
Usually the only way to
reduce the cheese factor is to come up with a
house rule that limits the flaw - like changing the points value of the item or limiting the number of times it can be used.