Jim Rossignol has a great take today on why he wants to play Day Z, XCOM, and FTL so much more than Dishonored: the more ways there are to fail, the more invested he becomes in a game.
Novelists and scriptwriters have understood this trick for years: piling problems on to the protagonist, in as many different ways as possible, is what makes for a good plot set up. How the protagonist brilliantly resolves or overcomes those problems (or not) will decide how good the story actually is.
Dishonored, as he says, is a too-much-power-fantasy, an observation that dovetails with Ben Richardson's review for us. That piece identified Dishonored's problem as having too many ways to succeed, "the Swiss Armification of gaming." I'd suggest that the more ways you have to fail, the more appropriate the inclusion of multiple ways to suceed becomes. Certainly there are many vectors to success in XCOM, but they never feel gratuitous because the game threatens you in so many ways. It feels like you have the tools to succeed, just barely, and never more.