I like a game that doesn't have dedicated tutorials, only a 10-second "this is how this mechanic is useful" situation. Perfect example: Starcraft II. Uh-oh, you've been dropped into a bad situation. Oh wait, you JUST got a new unit that is super effective against this exact kind of situation AND is really handy for this particular mission! Thanks, Starcraft II! Sure, maybe the very first level could be called a tutorial since it introduces you to the most basic "click to move here, click to gun down everything that looks at you funny" functions.