I think one of the most important factors of a successful game is how exciting it is, not only for the participants but for the spectators too. I liked the 2004 game, but the first few actual matches I saw, it was not that exciting, there wasn't much action on the field, but once teams got used to the game, it became a very different game. Personally, I thought Stack Attack was a very exciting game, with the robots slamming into the crates in the first 15 seconds, the constant battle to get more boxes on your side and the final fight for king of the hill... it was just all around fun!
Of course, just saying "exciting" is pretty broad, but then, the question doesn't ask what makes a game exciting! But the game could be as simple as drive your robot across the field, and while everyone could probably (I say probably because I will never underestimate my team's ability to make the simplest task confusing
) succeed at that, it would be snooze city. Throw in a couple of trenches, a slippery slope and some rounded objects to move around and things start looking up!
Heidi