I score the games I play based on various categories and use a /10 scoring system, with .5 numbers for the overall score.
Game Mechanics: The gameplay mechanics of the game. Self-explanatory.
Controls: The control scheme of the game.
Story: The story of the game, of course.
Music & Sound: The game's aural presentation.
Visuals: The game's graphical presentation.
Localization: The game's translation and how well it was adapted to English.
Replay Value: The game's lasting appeal.
1 - Abysmal: Has absolutely no redeeming aspects, and could not possibly be worse.
2 - Terrible: Maybe the idea was kind of good, the player might accidentally have fun, and/or there may be one small redeeming aspect, but generally a weak effort.
3 - Bad: Generally a lousy effort, but some aspects are average or slightly enjoyable.
4 - Poor: An admirable effort, but still falls short.
5 - Mediocre: Neither good nor bad.
6 - Fair: Okay, but not for everyone.
7 - Good: Fun, maybe slightly replayable, but may have some serious flaws preventing it from being as good as it could have been.
8 - Great: Very fun, but maybe has one major serious flaw preventing it from truly excelling.
9 - Excellent: Negligible flaws, but very, very good.
10 - Perfect: Could not possibly be any better.