An adjective describing clever (but grossly unfair) strategies that deliver easy wins or decisive blows to the unwary opposition - usually at the expense of a satisfying game. Basically, any smart arse manoeuvre that will would cause your bug eyed, red faced victim to garrotte you with your own mouse cord can be considered cheesy. e.g. In Total Annihilation, one of the cheesiest things you can do is build an Aircraft Factory and then a Transport Plane. Fly the transport over to the enemy base and, before they've had a chance build any defences, kidnap the enemy Commander with it. Then self destruct the transport plane. Ouch! Game over.
Deliberately abusing a glitch, programming oversight, bug or other weakness of the game engine, such as the often bad artificial intelligence of your enemies. If a PnP Dungeon Master would not allow it, it is probably cheese. The most famous examples are probably the "Fake Talk" (clicking on blue-circled creatures as if to talk to them, then immediately attacking them while they wait for you to initiate dialog) and Cloudkilling dragons off-screen.
n. 1) Any sequence of in-game events that happen because of plot rather than the players actions."Bob the Knight isn't dead after getting eaten by that Forest Troll, he got reincarnated by his Goddess because they need him for a storyline, what a load of cheese". syn. flange, plottage, plot. 2) Any sequence of in-game events that strike the speaker as bad gaming. "You can't recognise me by my boots, that's cheese!"