Tension in boardgames mostly comes from the probability that you may still win or lose. For example, a game where your chance of winning is 50-50, as far as you know, is going to be far more tense than a game where you’ve already won or lost the game.
This is especially important in co-op and solo games. There is a review by Shut Up and Sit Down where Quinn’s criticises Marvel Champions for “often not having an ending.” Since the game is deterministic during the turn, once the players realize they can win, they’ve won, and can stop playing.
It is a common problem in co-op games that at some point victory may be assured, and the final turns lose all tension. This problem is something that Matt Leacock appears to be designing around in his recent games. Pandemic can have this problem, if the players get the cards they need and the infection can no longer kill you, but Fate of the Fellowship generally won’t, since there is always a final dice roll.