Note: These are just my rambling thoughts. I don't think I can actually answer the question I pose.
Now, of course, everyone has their own reason for playing games. One thing that I enjoy in most of my games is the aspect of friendly intellectual competition that accompanies them. However, this requires that I have the chance to explore the game to a deeper level. The game should be replayable.
"What makes a game replayable?"
That's a great question! Each game seems to do this differently. I'll list a few examples below with an attempt to highlight one factor that makes the game replayable. (This is not meant to be exhaustive, by the way.)
Variable Victory Conditions
Like in Kingdom Builder, which got me thinking about replayability today, some games have victory conditions that change from game to game. In this example, scoring points will come from your ability to meet the conditions on the indicated cards for that particular game. This could make even the same combination of boards a different game from previous iterations because the strategy you will take to pursue victory must change with your conditions for scoring! This is not even mentioning another thing that this game does to add replayability (modular boards).
Variable pieces
Variable Card Decks
Like the others, Fire in the Lake causes players to adjust their strategies as the game is played. However, while victory conditions are no different from game to game, your path to victory will probably change drastically. In this game, cards increase replayability in two ways: 1) they determine player turn order, so you may have new opportunities arise if you and your "teammate" can make the most of your temporary advantages, and 2) they bring with them often powerful events, which can force you to make some extremely tough decisions based on the current state of affairs. In addition, not all of the cards will be used in a game.
Hidden Pieces
In Napoleon's Triumph, and certain other military/wargames, pieces are allocated by the players at the beginning the of the game into army groups. The identities of the units is known to the placing player, but unknown to the opponent until they are engaged in battle. While this doesn't sound like it will make the game super different each time, the placement of your pieces will in part determine your strategy for the battle - and whether you can foil your opponent's attempts to counter you. Good luck figuring out whether those blocks standing in your way are one-strength infantry or the elite Guard units!
Your Opponent
Last, but not least, you cannot underestimate the replayability that a good opponent brings to a game like Hive. They will keep you on your toes and force you to rethink the way you play the game, leading to new strategies and novel ways to use your pieces.
