There's a number of demos I've played multiple times. Recently I can think of Defense Grid since it was out before the game and had one of the levels that let you set your own path, that basically sold me completely on the game. Just Cause 2 was another one even with the 30 minute limit before the mod. The first Batman demo was great for going back to that one room again and again trying different strategies plus the fight at the start. Sanctum was another indie title that let me play over and over on a couple maps and sold me on it. I think I even played the Bulletstorm demo a few times as I learned the level + skill shots.
Neither Just Cause or Batman presented the areas as they are in the final game but gave you enough taste plus some freedom that you knew what the final game was going to be like.
Not saying I played any of these 30 times or maybe even double digits except Defense Grid, but one guy in the thread wants a three play limit, some come close to saying one time is enough. I hear some demos are even only up for like a week or something on consoles?
Enough demos aren't worth playing more than once because they give you like five to ten minutes of gameplay, then make you watch an unskippable movie and a bunch of screens about preorder bonuses. The ones that give you a meaty chunk make me, at least, more likely to want the game as I start running into the inherent boundaries of the content not imposed time limits or whatever.
I didn't play it multiple times, but I thought Rochard had a pretty nice demo that gave you all the basics, an hour or so to play around and left enough future content out. And I've always liked the new trend of demos that let you pick up where you left off when you buy the full game.
